refactored stb font library into a cleaner unix library

3 files changed, 3379 insertions, 0 deletions

diff --git a/sys/libfont/font.c b/sys/libfont/font.c
new file mode 100644
index 0000000..f7dfce7
--- /dev/null
+++ b/sys/libfont/font.c
@@ -0,0 +1,3298 @@
+#include <u.h>
+#include <libn.h>
+#include <libfont.h>
+
+#define SAMPLE 8     /* should not be > 255 */ 
+
+#define getshort(b)  getbytes((b), 2)
+#define getint(b)    getbytes((b), 4)
+
+// -----------------------------------------------------------------------
+// internal types
+
+typedef struct Buffer      Buffer;
+typedef struct Edge        Edge;
+typedef struct ActiveEdge  ActiveEdge;
+typedef struct Point       Point;
+
+struct Buffer
+{
+   uchar *data;
+   int cursor;
+   int size;
+};
+
+struct Edge {
+   float x0, y0, x1,y1;
+   int invert;
+};
+
+struct ActiveEdge
+{
+   struct ActiveEdge *next;
+   float fx,fdx,fdy;
+   float direction;
+   float sy;
+   float ey;
+};
+
+struct Point
+{
+   float x,y;
+};
+
+// -----------------------------------------------------------------------
+// opaque external types
+
+struct font·Info
+{
+   void   *userdata;
+   uchar  *data;                     // pointer to .ttf file
+   int    fontstart;                 // offset of start of font
+
+   int numglyphs;                    // number of glyphs, needed for range checking
+
+   int loca,head,glyf,hhea,hmtx,kern,gpos,svg; // table locations as offset from start of .ttf
+   int index_map;                   // a cmap mapping for our chosen character encoding
+   int indexToLocFormat;            // format needed to map from glyph index to glyph
+
+   Buffer cff;                    // cff font data
+   Buffer charstrings;            // the charstring index
+   Buffer gsubrs;                 // global charstring subroutines index
+   Buffer subrs;                  // private charstring subroutines index
+   Buffer fontdicts;              // array of font dicts
+   Buffer fdselect;               // map from glyph to fontdict
+};
+
+struct font·Bitmap
+{
+   int    w;
+   int    h;
+   int    stride;
+   uchar *pixels;
+}; 
+
+typedef int test_oversample_pow2[(SAMPLE & (SAMPLE-1)) == 0 ? 1 : -1];
+
+// -----------------------------------------------------------------------
+// buf helpers to parse data from file
+
+static 
+uchar 
+getbyte(Buffer *b)
+{
+   if (b->cursor >= b->size)
+      return 0;
+   return b->data[b->cursor++];
+}
+
+static
+uchar
+peek(Buffer *b)
+{
+   if (b->cursor >= b->size)
+      return 0;
+   return b->data[b->cursor];
+}
+
+static 
+void 
+seek(Buffer *b, int o)
+{
+   assert(!(o > b->size || o < 0));
+   b->cursor = (o > b->size || o < 0) ? b->size : o;
+}
+
+static 
+void 
+skip(Buffer *b, int o)
+{
+   seek(b, b->cursor + o);
+}
+
+static 
+uint32 
+getbytes(Buffer *b, int n)
+{
+   uint32 v = 0;
+   int i;
+   assert(n >= 1 && n <= 4);
+   for (i = 0; i < n; i++)
+      v = (v << 8) | getbyte(b);
+   return v;
+}
+
+static 
+Buffer 
+makebuf(const void *p, size_t size)
+{
+   Buffer r;
+   assert(size < 0x40000000);
+   r.data = (uchar*) p;
+   r.size = (int) size;
+   r.cursor = 0;
+   return r;
+}
+
+static 
+Buffer 
+slice(const Buffer *b, int o, int s)
+{
+   Buffer r = makebuf(nil, 0);
+   if (o < 0 || s < 0 || o > b->size || s > b->size - o) return r;
+   r.data = b->data + o;
+   r.size = s;
+   return r;
+}
+
+static 
+Buffer 
+cff_index(Buffer *b)
+{
+   int count, start, offsize;
+
+   start = b->cursor;
+   count = getshort(b);
+   if (count) {
+      offsize = getbyte(b);
+      assert(offsize >= 1 && offsize <= 4);
+      skip(b, offsize * count);
+      skip(b, getbytes(b, offsize) - 1);
+   }
+   return slice(b, start, b->cursor - start);
+}
+
+static 
+uint32 
+cff_int(Buffer *b)
+{
+   int b0 = getbyte(b);
+   if (b0 >= 32 && b0 <= 246)       return b0 - 139;
+   else if (b0 >= 247 && b0 <= 250) return (b0 - 247)*256 + getbyte(b) + 108;
+   else if (b0 >= 251 && b0 <= 254) return -(b0 - 251)*256 - getbyte(b) - 108;
+   else if (b0 == 28)               return getshort(b);
+   else if (b0 == 29)               return getint(b);
+   assert(0);
+   return 0;
+}
+
+static 
+void 
+skip_operand(Buffer *b) {
+   int v, b0 = peek(b);
+   assert(b0 >= 28);
+   if (b0 == 30) {
+      skip(b, 1);
+      while (b->cursor < b->size) {
+         v = getbyte(b);
+         if ((v & 0xF) == 0xF || (v >> 4) == 0xF)
+            break;
+      }
+   } else {
+      cff_int(b);
+   }
+}
+
+static 
+Buffer 
+dict_get(Buffer *b, int key)
+{
+   seek(b, 0);
+   while (b->cursor < b->size) {
+      int start = b->cursor, end, op;
+      while (peek(b) >= 28)
+         skip_operand(b);
+      end = b->cursor;
+      op = getbyte(b);
+      if (op == 12)  op = getbyte(b) | 0x100;
+      if (op == key) return slice(b, start, end-start);
+   }
+   return slice(b, 0, 0);
+}
+
+static 
+void 
+dict_get_ints(Buffer *b, int key, int outcount, uint32 *out)
+{
+   int i;
+   Buffer operands = dict_get(b, key);
+   for (i = 0; i < outcount && operands.cursor < operands.size; i++)
+      out[i] = cff_int(&operands);
+}
+
+static 
+int 
+cff_index_count(Buffer *b)
+{
+   seek(b, 0);
+   return getshort(b);
+}
+
+static 
+Buffer 
+cff_index_get(Buffer b, int i)
+{
+   int count, offsize, start, end;
+   seek(&b, 0);
+   count = getshort(&b);
+   offsize = getbyte(&b);
+   assert(i >= 0 && i < count);
+   assert(offsize >= 1 && offsize <= 4);
+   skip(&b, i*offsize);
+   start = getbytes(&b, offsize);
+   end = getbytes(&b, offsize);
+   return slice(&b, 2+(count+1)*offsize+start, end - start);
+}
+
+// -----------------------------------------------------------------------
+// accessors to parse data from file
+
+/* 
+ * on platforms that don't allow misaligned reads, if we want to allow
+ * truetype fonts that aren't padded to alignment, define ALLOW_UNALIGNED_TRUETYPE
+ */
+
+#define ttBYTE(p)     (* (uchar *) (p))
+#define ttCHAR(p)     (* (char *) (p))
+#define ttFixed(p)    ttLONG(p)
+
+static ushort ttUSHORT(uchar *p) { return p[0]*256 + p[1]; }
+static short ttSHORT(uchar *p)   { return p[0]*256 + p[1]; }
+static uint32 ttULONG(uchar *p)  { return (p[0]<<24) + (p[1]<<16) + (p[2]<<8) + p[3]; }
+static int32 ttLONG(uchar *p)    { return (p[0]<<24) + (p[1]<<16) + (p[2]<<8) + p[3]; }
+
+#define font·tag4(p,c0,c1,c2,c3) ((p)[0] == (c0) && (p)[1] == (c1) && (p)[2] == (c2) && (p)[3] == (c3))
+#define font·tag(p,str)           font·tag4(p,str[0],str[1],str[2],str[3])
+
+static 
+int 
+isfont(uchar *font)
+{
+   // check the version number
+   if (font·tag4(font, '1',0,0,0))  return 1; // TrueType 1
+   if (font·tag(font, "typ1"))      return 1; // TrueType with type 1 font -- we don't support this!
+   if (font·tag(font, "OTTO"))      return 1; // OpenType with CFF
+   if (font·tag4(font, 0,1,0,0))    return 1; // OpenType 1.0
+   if (font·tag(font, "true"))      return 1; // Apple specification for TrueType fonts
+
+   return 0;
+}
+
+// @OPTIMIZE: binary search
+static 
+uint32 
+find_table(uchar *data, uint32 fontstart, const char *tag)
+{
+   int i;
+   int32 ntab;    
+   uint32 tabdir; 
+
+   ntab   = ttUSHORT(data+fontstart+4); 
+   tabdir = fontstart + 12;
+   for (i=0; i < ntab; ++i) {
+      uint32 loc = tabdir + 16*i;
+      if (font·tag(data+loc+0, tag))
+         return ttULONG(data+loc+8);
+   }
+   return 0;
+}
+
+int
+font·offsetfor(uchar *font_collection, int index)
+{
+   // if it's just a font, there's only one valid index
+   if (isfont(font_collection))
+      return index == 0 ? 0 : -1;
+
+   // check if it's a TTC
+   if (font·tag(font_collection, "ttcf")) {
+      // version 1?
+      if (ttULONG(font_collection+4) == 0x00010000 || ttULONG(font_collection+4) == 0x00020000) {
+         int32 n = ttLONG(font_collection+8);
+         if (index >= n)
+            return -1;
+         return ttULONG(font_collection+12+index*4);
+      }
+   }
+   return -1;
+}
+
+int 
+font·number(uchar *font_collection)
+{
+   // if it's just a font, there's only one valid font
+   if (isfont(font_collection))
+      return 1;
+
+   // check if it's a TTC
+   if (font·tag(font_collection, "ttcf")) {
+      // version 1?
+      if (ttULONG(font_collection+4) == 0x00010000 || ttULONG(font_collection+4) == 0x00020000) {
+         return ttLONG(font_collection+8);
+      }
+   }
+   return 0;
+}
+
+static 
+Buffer 
+get_subrs(Buffer cff, Buffer fontdict)
+{
+   uint32 subrsoff = 0, private_loc[2] = { 0, 0 };
+   Buffer pdict;
+   dict_get_ints(&fontdict, 18, 2, private_loc);
+   if (!private_loc[1] || !private_loc[0]) return makebuf(nil, 0);
+   pdict = slice(&cff, private_loc[1], private_loc[0]);
+   dict_get_ints(&pdict, 19, 1, &subrsoff);
+   if (!subrsoff) return makebuf(nil, 0);
+   seek(&cff, private_loc[1]+subrsoff);
+   return cff_index(&cff);
+}
+
+// since most people won't use this, find this table the first time it's needed
+static 
+int 
+get_svg(font·Info *info)
+{
+   uint32 t;
+   if (info->svg < 0) {
+      t = find_table(info->data, info->fontstart, "SVG ");
+      if (t) {
+         uint32 offset = ttULONG(info->data + t + 2);
+         info->svg = t + offset;
+      } else {
+         info->svg = 0;
+      }
+   }
+   return info->svg;
+}
+
+static
+int 
+init(font·Info *info, uchar *data, int fontstart)
+{
+   uint32 cmap, t;
+   int32 i,numTables;
+
+   info->data = data;
+   info->fontstart = fontstart;
+   info->cff = makebuf(nil, 0);
+
+   cmap       = find_table(data, fontstart, "cmap"); // required
+   info->loca = find_table(data, fontstart, "loca"); // required
+   info->head = find_table(data, fontstart, "head"); // required
+   info->glyf = find_table(data, fontstart, "glyf"); // required
+   info->hhea = find_table(data, fontstart, "hhea"); // required
+   info->hmtx = find_table(data, fontstart, "hmtx"); // required
+   info->kern = find_table(data, fontstart, "kern"); // not required
+   info->gpos = find_table(data, fontstart, "GPOS"); // not required
+
+   if (!cmap || !info->head || !info->hhea || !info->hmtx)
+      return 0;
+   if (info->glyf) {
+      // required for truetype
+      if (!info->loca) 
+          return 1;
+   } else {
+      // initialization for CFF / Type2 fonts (OTF)
+      Buffer b, topdict, topdictidx;
+      uint32 cstype = 2, charstrings = 0, fdarrayoff = 0, fdselectoff = 0;
+      uint32 cff;
+
+      cff = find_table(data, fontstart, "CFF ");
+      if (!cff) 
+          return 1;
+
+      info->fontdicts = makebuf(nil, 0);
+      info->fdselect = makebuf(nil, 0);
+
+      // @TODO this should use size from table (not 512MB)
+      info->cff = makebuf(data+cff, 512*1024*1024);
+      b = info->cff;
+
+      // read the header
+      skip(&b, 2);
+      seek(&b, getbyte(&b)); // hdrsize
+
+      // @TODO the name INDEX could list multiple fonts,
+      // but we just use the first one.
+      cff_index(&b);  // name INDEX
+      topdictidx = cff_index(&b);
+      topdict = cff_index_get(topdictidx, 0);
+      cff_index(&b);  // string INDEX
+      info->gsubrs = cff_index(&b);
+
+      dict_get_ints(&topdict, 17, 1, &charstrings);
+      dict_get_ints(&topdict, 0x100 | 6, 1, &cstype);
+      dict_get_ints(&topdict, 0x100 | 36, 1, &fdarrayoff);
+      dict_get_ints(&topdict, 0x100 | 37, 1, &fdselectoff);
+      info->subrs = get_subrs(b, topdict);
+
+      // we only support Type 2 charstrings
+      if (cstype != 2) 
+          return 1;
+      if (charstrings == 0) 
+          return 1;
+
+      if (fdarrayoff) {
+         // looks like a CID font
+         if (!fdselectoff) 
+             return 1;
+         seek(&b, fdarrayoff);
+         info->fontdicts = cff_index(&b);
+         info->fdselect = slice(&b, fdselectoff, b.size-fdselectoff);
+      }
+
+      seek(&b, charstrings);
+      info->charstrings = cff_index(&b);
+   }
+
+   t = find_table(data, fontstart, "maxp");
+   if (t)
+      info->numglyphs = ttUSHORT(data+t+4);
+   else
+      info->numglyphs = 0xffff;
+
+   info->svg = -1;
+
+   // find a cmap encoding table we understand *now* to avoid searching
+   // later. (todo: could make this installable)
+   // the same regardless of glyph.
+   numTables = ttUSHORT(data + cmap + 2);
+   info->index_map = 0;
+   for (i=0; i < numTables; ++i) {
+      uint32 encoding_record = cmap + 4 + 8 * i;
+      // find an encoding we understand:
+      switch(ttUSHORT(data+encoding_record)) {
+        case font·platform_unicode:
+            // Mac/iOS has these
+            // all the encodingIDs are unicode, so we don't bother to check it
+            info->index_map = cmap + ttULONG(data+encoding_record+4);
+            break;
+        default:
+            ;
+      }
+   }
+   if (info->index_map == 0) {
+      return 1;
+   }
+
+   info->indexToLocFormat = ttUSHORT(data+info->head + 50);
+   return 0;
+}
+
+font·Info *
+font·make(uchar *data, int fontstart)
+{
+    int err;
+    font·Info *info;
+
+    info = calloc(1, sizeof(*info));
+    err  = init(info, data, fontstart);
+    if (err) {
+        free(info);
+        info = nil;
+    }
+
+    return info;
+}
+
+void
+font·free(font·Info *info)
+{
+    free(info);
+}
+
+int 
+font·glyph_index(font·Info *info, int unicode_codepoint)
+{
+   uchar *data = info->data;
+   uint32 index_map = info->index_map;
+
+   ushort format = ttUSHORT(data + index_map + 0);
+   if (format == 0) { // apple byte encoding
+      int32 bytes = ttUSHORT(data + index_map + 2);
+      if (unicode_codepoint < bytes-6)
+         return ttBYTE(data + index_map + 6 + unicode_codepoint);
+      return 0;
+   } else if (format == 6) {
+      uint32 first = ttUSHORT(data + index_map + 6);
+      uint32 count = ttUSHORT(data + index_map + 8);
+      if ((uint32) unicode_codepoint >= first && (uint32) unicode_codepoint < first+count)
+         return ttUSHORT(data + index_map + 10 + (unicode_codepoint - first)*2);
+      return 0;
+   } else if (format == 2) {
+      assert(0); // @TODO: high-byte mapping for japanese/chinese/korean
+      return 0;
+   } else if (format == 4) { // standard mapping for windows fonts: binary search collection of ranges
+      ushort segcount = ttUSHORT(data+index_map+6) >> 1;
+      ushort searchRange = ttUSHORT(data+index_map+8) >> 1;
+      ushort entrySelector = ttUSHORT(data+index_map+10);
+      ushort rangeShift = ttUSHORT(data+index_map+12) >> 1;
+
+      // do a binary search of the segments
+      uint32 endCount = index_map + 14;
+      uint32 search = endCount;
+
+      if (unicode_codepoint > 0xffff)
+         return 0;
+
+      // they lie from endCount .. endCount + segCount
+      // but searchRange is the nearest power of two, so...
+      if (unicode_codepoint >= ttUSHORT(data + search + rangeShift*2))
+         search += rangeShift*2;
+
+      // now decrement to bias correctly to find smallest
+      search -= 2;
+      while (entrySelector) {
+         ushort end;
+         searchRange >>= 1;
+         end = ttUSHORT(data + search + searchRange*2);
+         if (unicode_codepoint > end)
+            search += searchRange*2;
+         --entrySelector;
+      }
+      search += 2;
+
+      {
+         ushort offset, start;
+         ushort item = (ushort) ((search - endCount) >> 1);
+
+         assert(unicode_codepoint <= ttUSHORT(data + endCount + 2*item));
+         start = ttUSHORT(data + index_map + 14 + segcount*2 + 2 + 2*item);
+         if (unicode_codepoint < start)
+            return 0;
+
+         offset = ttUSHORT(data + index_map + 14 + segcount*6 + 2 + 2*item);
+         if (offset == 0)
+            return (ushort) (unicode_codepoint + ttSHORT(data + index_map + 14 + segcount*4 + 2 + 2*item));
+
+         return ttUSHORT(data + offset + (unicode_codepoint-start)*2 + index_map + 14 + segcount*6 + 2 + 2*item);
+      }
+   } else if (format == 12 || format == 13) {
+      uint32 ngroups = ttULONG(data+index_map+12);
+      int32 low,high;
+      low = 0; high = (int32)ngroups;
+      // Binary search the right group.
+      while (low < high) {
+         int32 mid = low + ((high-low) >> 1); // rounds down, so low <= mid < high
+         uint32 start_char = ttULONG(data+index_map+16+mid*12);
+         uint32 end_char = ttULONG(data+index_map+16+mid*12+4);
+         if ((uint32) unicode_codepoint < start_char)
+            high = mid;
+         else if ((uint32) unicode_codepoint > end_char)
+            low = mid+1;
+         else {
+            uint32 start_glyph = ttULONG(data+index_map+16+mid*12+8);
+            if (format == 12)
+               return start_glyph + unicode_codepoint-start_char;
+            else // format == 13
+               return start_glyph;
+         }
+      }
+      return 0; // not found
+   }
+   // @TODO
+   assert(0);
+   return 0;
+}
+
+int 
+font·code_shape(font·Info *info, int unicode_codepoint, font·Vertex **vertices)
+{
+   return font·glyph_shape(info, font·glyph_index(info, unicode_codepoint), vertices);
+}
+
+static
+void 
+setvertex(font·Vertex *v, uchar type, int32 x, int32 y, int32 cx, int32 cy)
+{
+   v->type = type;
+   v->x = (short) x;
+   v->y = (short) y;
+   v->cx = (short) cx;
+   v->cy = (short) cy;
+}
+
+static 
+int 
+glyph_offset(const font·Info *info, int glyph_index)
+{
+   int g1,g2;
+
+   assert(!info->cff.size);
+
+   if (glyph_index >= info->numglyphs) return -1; // glyph index out of range
+   if (info->indexToLocFormat >= 2)    return -1; // unknown index->glyph map format
+
+   if (info->indexToLocFormat == 0) {
+      g1 = info->glyf + ttUSHORT(info->data + info->loca + glyph_index * 2) * 2;
+      g2 = info->glyf + ttUSHORT(info->data + info->loca + glyph_index * 2 + 2) * 2;
+   } else {
+      g1 = info->glyf + ttULONG (info->data + info->loca + glyph_index * 4);
+      g2 = info->glyf + ttULONG (info->data + info->loca + glyph_index * 4 + 4);
+   }
+
+   return g1==g2 ? -1 : g1; // if length is 0, return -1
+}
+
+static int glyph_info_t2(font·Info *info, int glyph_index, int *x0, int *y0, int *x1, int *y1);
+
+int 
+font·glyph_box(font·Info *info, int glyph_index, int *x0, int *y0, int *x1, int *y1)
+{
+   if (info->cff.size) {
+      glyph_info_t2(info, glyph_index, x0, y0, x1, y1);
+   } else {
+      int g = glyph_offset(info, glyph_index);
+      if (g < 0) return 0;
+
+      if (x0) *x0 = ttSHORT(info->data + g + 2);
+      if (y0) *y0 = ttSHORT(info->data + g + 4);
+      if (x1) *x1 = ttSHORT(info->data + g + 6);
+      if (y1) *y1 = ttSHORT(info->data + g + 8);
+   }
+   return 1;
+}
+
+int 
+font·code_box(font·Info *info, int codepoint, int *x0, int *y0, int *x1, int *y1)
+{
+   return font·glyph_box(info, font·glyph_index(info,codepoint), x0,y0,x1,y1);
+}
+
+int 
+font·glyph_empty(font·Info *info, int glyph_index)
+{
+   short numberOfContours;
+   int g;
+   if (info->cff.size)
+      return glyph_info_t2(info, glyph_index, nil, nil, nil, nil) == 0;
+   g = glyph_offset(info, glyph_index);
+   if (g < 0) return 1;
+   numberOfContours = ttSHORT(info->data + g);
+   return numberOfContours == 0;
+}
+
+static 
+int 
+close_shape(font·Vertex *vertices, int num_vertices, int was_off, int start_off,
+    int32 sx, int32 sy, int32 scx, int32 scy, int32 cx, int32 cy)
+{
+   if (start_off) {
+      if (was_off)
+         setvertex(&vertices[num_vertices++], font·Vcurve, (cx+scx)>>1, (cy+scy)>>1, cx,cy);
+      setvertex(&vertices[num_vertices++], font·Vcurve, sx,sy,scx,scy);
+   } else {
+      if (was_off)
+         setvertex(&vertices[num_vertices++], font·Vcurve,sx,sy,cx,cy);
+      else
+         setvertex(&vertices[num_vertices++], font·Vline,sx,sy,0,0);
+   }
+   return num_vertices;
+}
+
+static 
+int 
+glyph_shape_tt(font·Info *info, int glyph_index, font·Vertex **pvertices)
+{
+   short numberOfContours;
+   uchar *endPtsOfContours;
+   uchar *data = info->data;
+   font·Vertex *vertices=0;
+   int num_vertices=0;
+   int g = glyph_offset(info, glyph_index);
+
+   *pvertices = nil;
+
+   if (g < 0) return 0;
+
+   numberOfContours = ttSHORT(data + g);
+
+   if (numberOfContours > 0) {
+      uchar flags=0,flagcount;
+      int32 ins, i,j=0,m,n, next_move, was_off=0, off, start_off=0;
+      int32 x,y,cx,cy,sx,sy, scx,scy;
+      uchar *points;
+      endPtsOfContours = (data + g + 10);
+      ins = ttUSHORT(data + g + 10 + numberOfContours * 2);
+      points = data + g + 10 + numberOfContours * 2 + 2 + ins;
+
+      n = 1+ttUSHORT(endPtsOfContours + numberOfContours*2-2);
+
+      m = n + 2*numberOfContours;  // a loose bound on how many vertices we might need
+      vertices = malloc(m * sizeof(vertices[0]));
+      if (vertices == 0)
+         return 0;
+
+      next_move = 0;
+      flagcount=0;
+
+      // in first pass, we load uninterpreted data into the allocated array
+      // above, shifted to the end of the array so we won't overwrite it when
+      // we create our final data starting from the front
+
+      off = m - n; // starting offset for uninterpreted data, regardless of how m ends up being calculated
+
+      // first load flags
+
+      for (i=0; i < n; ++i) {
+         if (flagcount == 0) {
+            flags = *points++;
+            if (flags & 8)
+               flagcount = *points++;
+         } else
+            --flagcount;
+         vertices[off+i].type = flags;
+      }
+
+      // now load x coordinates
+      x=0;
+      for (i=0; i < n; ++i) {
+         flags = vertices[off+i].type;
+         if (flags & 2) {
+            short dx = *points++;
+            x += (flags & 16) ? dx : -dx; // ???
+         } else {
+            if (!(flags & 16)) {
+               x = x + (short) (points[0]*256 + points[1]);
+               points += 2;
+            }
+         }
+         vertices[off+i].x = (short) x;
+      }
+
+      // now load y coordinates
+      y=0;
+      for (i=0; i < n; ++i) {
+         flags = vertices[off+i].type;
+         if (flags & 4) {
+            short dy = *points++;
+            y += (flags & 32) ? dy : -dy; // ???
+         } else {
+            if (!(flags & 32)) {
+               y = y + (short) (points[0]*256 + points[1]);
+               points += 2;
+            }
+         }
+         vertices[off+i].y = (short) y;
+      }
+
+      // now convert them to our format
+      num_vertices=0;
+      sx = sy = cx = cy = scx = scy = 0;
+      for (i=0; i < n; ++i) {
+         flags = vertices[off+i].type;
+         x     = (short) vertices[off+i].x;
+         y     = (short) vertices[off+i].y;
+
+         if (next_move == i) {
+            if (i != 0)
+               num_vertices = close_shape(vertices, num_vertices, was_off, start_off, sx,sy,scx,scy,cx,cy);
+
+            // now start the new one
+            start_off = !(flags & 1);
+            if (start_off) {
+               // if we start off with an off-curve point, then when we need to find a point on the curve
+               // where we can start, and we need to save some state for when we wraparound.
+               scx = x;
+               scy = y;
+               if (!(vertices[off+i+1].type & 1)) {
+                  // next point is also a curve point, so interpolate an on-point curve
+                  sx = (x + (int32) vertices[off+i+1].x) >> 1;
+                  sy = (y + (int32) vertices[off+i+1].y) >> 1;
+               } else {
+                  // otherwise just use the next point as our start point
+                  sx = (int32) vertices[off+i+1].x;
+                  sy = (int32) vertices[off+i+1].y;
+                  ++i; // we're using point i+1 as the starting point, so skip it
+               }
+            } else {
+               sx = x;
+               sy = y;
+            }
+            setvertex(&vertices[num_vertices++], font·Vmove,sx,sy,0,0);
+            was_off = 0;
+            next_move = 1 + ttUSHORT(endPtsOfContours+j*2);
+            ++j;
+         } else {
+            if (!(flags & 1)) { // if it's a curve
+               if (was_off) // two off-curve control points in a row means interpolate an on-curve midpoint
+                  setvertex(&vertices[num_vertices++], font·Vcurve, (cx+x)>>1, (cy+y)>>1, cx, cy);
+               cx = x;
+               cy = y;
+               was_off = 1;
+            } else {
+               if (was_off)
+                  setvertex(&vertices[num_vertices++], font·Vcurve, x,y, cx, cy);
+               else
+                  setvertex(&vertices[num_vertices++], font·Vline, x,y,0,0);
+               was_off = 0;
+            }
+         }
+      }
+      num_vertices = close_shape(vertices, num_vertices, was_off, start_off, sx,sy,scx,scy,cx,cy);
+   } else if (numberOfContours < 0) {
+      // Compound shapes.
+      int more = 1;
+      uchar *comp = data + g + 10;
+      num_vertices = 0;
+      vertices = 0;
+      while (more) {
+         ushort flags, gidx;
+         int comp_num_verts = 0, i;
+         font·Vertex *comp_verts = 0, *tmp = 0;
+         float mtx[6] = {1,0,0,1,0,0}, m, n;
+
+         flags = ttSHORT(comp); comp+=2;
+         gidx = ttSHORT(comp); comp+=2;
+
+         if (flags & 2) { // XY values
+            if (flags & 1) { // shorts
+               mtx[4] = ttSHORT(comp); comp+=2;
+               mtx[5] = ttSHORT(comp); comp+=2;
+            } else {
+               mtx[4] = ttCHAR(comp); comp+=1;
+               mtx[5] = ttCHAR(comp); comp+=1;
+            }
+         }
+         else {
+            // @TODO handle matching point
+            assert(0);
+         }
+         if (flags & (1<<3)) { // WE_HAVE_A_SCALE
+            mtx[0] = mtx[3] = ttSHORT(comp)/16384.0f; comp+=2;
+            mtx[1] = mtx[2] = 0;
+         } else if (flags & (1<<6)) { // WE_HAVE_AN_X_AND_YSCALE
+            mtx[0] = ttSHORT(comp)/16384.0f; comp+=2;
+            mtx[1] = mtx[2] = 0;
+            mtx[3] = ttSHORT(comp)/16384.0f; comp+=2;
+         } else if (flags & (1<<7)) { // WE_HAVE_A_TWO_BY_TWO
+            mtx[0] = ttSHORT(comp)/16384.0f; comp+=2;
+            mtx[1] = ttSHORT(comp)/16384.0f; comp+=2;
+            mtx[2] = ttSHORT(comp)/16384.0f; comp+=2;
+            mtx[3] = ttSHORT(comp)/16384.0f; comp+=2;
+         }
+
+         // Find transformation scales.
+         m = (float) sqrt(mtx[0]*mtx[0] + mtx[1]*mtx[1]);
+         n = (float) sqrt(mtx[2]*mtx[2] + mtx[3]*mtx[3]);
+
+         // Get indexed glyph.
+         comp_num_verts = font·glyph_shape(info, gidx, &comp_verts);
+         if (comp_num_verts > 0) {
+            // Transform vertices.
+            for (i = 0; i < comp_num_verts; ++i) {
+               font·Vertex* v = &comp_verts[i];
+               short x,y;
+               x=v->x; y=v->y;
+               v->x = (short)(m * (mtx[0]*x + mtx[2]*y + mtx[4]));
+               v->y = (short)(n * (mtx[1]*x + mtx[3]*y + mtx[5]));
+               x=v->cx; y=v->cy;
+               v->cx = (short)(m * (mtx[0]*x + mtx[2]*y + mtx[4]));
+               v->cy = (short)(n * (mtx[1]*x + mtx[3]*y + mtx[5]));
+            }
+            // Append vertices.
+            tmp = malloc((num_vertices+comp_num_verts)*sizeof(font·Vertex));
+            if (!tmp) {
+               if (vertices) free(vertices);
+               if (comp_verts) free(comp_verts);
+               return 0;
+            }
+            if (num_vertices > 0) 
+                memcpy(tmp, vertices, num_vertices*sizeof(font·Vertex));
+
+            memcpy(tmp+num_vertices, comp_verts, comp_num_verts*sizeof(font·Vertex));
+
+            if (vertices) 
+                free(vertices);
+
+            vertices = tmp;
+            free(comp_verts);
+            num_vertices += comp_num_verts;
+         }
+         // More components ?
+         more = flags & (1<<5);
+      }
+   } else {
+      // numberOfCounters == 0, do nothing
+   }
+
+   *pvertices = vertices;
+   return num_vertices;
+}
+
+typedef struct
+{
+   int bounds;
+   int started;
+   float first_x, first_y;
+   float x, y;
+   int32 min_x, max_x, min_y, max_y;
+
+   font·Vertex *pvertices;
+   int num_vertices;
+} csctx;
+
+#define CSCTX_INIT(bounds) {bounds,0, 0,0, 0,0, 0,0,0,0, nil, 0}
+
+static void track_vertex(csctx *c, int32 x, int32 y)
+{
+   if (x > c->max_x || !c->started) c->max_x = x;
+   if (y > c->max_y || !c->started) c->max_y = y;
+   if (x < c->min_x || !c->started) c->min_x = x;
+   if (y < c->min_y || !c->started) c->min_y = y;
+   c->started = 1;
+}
+
+static void csctx_v(csctx *c, uchar type, int32 x, int32 y, int32 cx, int32 cy, int32 cx1, int32 cy1)
+{
+   if (c->bounds) {
+      track_vertex(c, x, y);
+      if (type == font·Vcubic) {
+         track_vertex(c, cx, cy);
+         track_vertex(c, cx1, cy1);
+      }
+   } else {
+      setvertex(&c->pvertices[c->num_vertices], type, x, y, cx, cy);
+      c->pvertices[c->num_vertices].cx1 = (short) cx1;
+      c->pvertices[c->num_vertices].cy1 = (short) cy1;
+   }
+   c->num_vertices++;
+}
+
+static void csctx_close_shape(csctx *ctx)
+{
+   if (ctx->first_x != ctx->x || ctx->first_y != ctx->y)
+      csctx_v(ctx, font·Vline, (int)ctx->first_x, (int)ctx->first_y, 0, 0, 0, 0);
+}
+
+static void csctx_rmove_to(csctx *ctx, float dx, float dy)
+{
+   csctx_close_shape(ctx);
+   ctx->first_x = ctx->x = ctx->x + dx;
+   ctx->first_y = ctx->y = ctx->y + dy;
+   csctx_v(ctx, font·Vmove, (int)ctx->x, (int)ctx->y, 0, 0, 0, 0);
+}
+
+static void csctx_rline_to(csctx *ctx, float dx, float dy)
+{
+   ctx->x += dx;
+   ctx->y += dy;
+   csctx_v(ctx, font·Vline, (int)ctx->x, (int)ctx->y, 0, 0, 0, 0);
+}
+
+static void csctx_rccurve_to(csctx *ctx, float dx1, float dy1, float dx2, float dy2, float dx3, float dy3)
+{
+   float cx1 = ctx->x + dx1;
+   float cy1 = ctx->y + dy1;
+   float cx2 = cx1 + dx2;
+   float cy2 = cy1 + dy2;
+   ctx->x = cx2 + dx3;
+   ctx->y = cy2 + dy3;
+   csctx_v(ctx, font·Vcubic, (int)ctx->x, (int)ctx->y, (int)cx1, (int)cy1, (int)cx2, (int)cy2);
+}
+
+static Buffer get_subr(Buffer idx, int n)
+{
+   int count = cff_index_count(&idx);
+   int bias = 107;
+   if (count >= 33900)
+      bias = 32768;
+   else if (count >= 1240)
+      bias = 1131;
+   n += bias;
+   if (n < 0 || n >= count)
+      return makebuf(nil, 0);
+   return cff_index_get(idx, n);
+}
+
+static Buffer cid_get_glyph_subrs(const font·Info *info, int glyph_index)
+{
+   Buffer fdselect = info->fdselect;
+   int nranges, start, end, v, fmt, fdselector = -1, i;
+
+   seek(&fdselect, 0);
+   fmt = getbyte(&fdselect);
+   if (fmt == 0) {
+      // untested
+      skip(&fdselect, glyph_index);
+      fdselector = getbyte(&fdselect);
+   } else if (fmt == 3) {
+      nranges = getshort(&fdselect);
+      start = getshort(&fdselect);
+      for (i = 0; i < nranges; i++) {
+         v = getbyte(&fdselect);
+         end = getshort(&fdselect);
+         if (glyph_index >= start && glyph_index < end) {
+            fdselector = v;
+            break;
+         }
+         start = end;
+      }
+   }
+   if (fdselector == -1) makebuf(nil, 0);
+   return get_subrs(info->cff, cff_index_get(info->fontdicts, fdselector));
+}
+
+static 
+int 
+run_charstring(font·Info *info, int glyph_index, csctx *c)
+{
+   int in_header = 1, maskbits = 0, subr_stack_height = 0, sp = 0, v, i, b0;
+   int has_subrs = 0, clear_stack;
+   float s[48];
+   Buffer subr_stack[10], subrs = info->subrs, b;
+   float f;
+
+#define STBTT__CSERR(s) (0)
+
+   // this currently ignores the initial width value, which isn't needed if we have hmtx
+   b = cff_index_get(info->charstrings, glyph_index);
+   while (b.cursor < b.size) {
+      i = 0;
+      clear_stack = 1;
+      b0 = getbyte(&b);
+      switch (b0) {
+      // @TODO implement hinting
+      case 0x13: // hintmask
+      case 0x14: // cntrmask
+         if (in_header)
+            maskbits += (sp / 2); // implicit "vstem"
+         in_header = 0;
+         skip(&b, (maskbits + 7) / 8);
+         break;
+
+      case 0x01: // hstem
+      case 0x03: // vstem
+      case 0x12: // hstemhm
+      case 0x17: // vstemhm
+         maskbits += (sp / 2);
+         break;
+
+      case 0x15: // rmoveto
+         in_header = 0;
+         if (sp < 2) return STBTT__CSERR("rmoveto stack");
+         csctx_rmove_to(c, s[sp-2], s[sp-1]);
+         break;
+      case 0x04: // vmoveto
+         in_header = 0;
+         if (sp < 1) return STBTT__CSERR("vmoveto stack");
+         csctx_rmove_to(c, 0, s[sp-1]);
+         break;
+      case 0x16: // hmoveto
+         in_header = 0;
+         if (sp < 1) return STBTT__CSERR("hmoveto stack");
+         csctx_rmove_to(c, s[sp-1], 0);
+         break;
+
+      case 0x05: // rlineto
+         if (sp < 2) return STBTT__CSERR("rlineto stack");
+         for (; i + 1 < sp; i += 2)
+            csctx_rline_to(c, s[i], s[i+1]);
+         break;
+
+      // hlineto/vlineto and vhcurveto/hvcurveto alternate horizontal and vertical
+      // starting from a different place.
+
+      case 0x07: // vlineto
+         if (sp < 1) return STBTT__CSERR("vlineto stack");
+         goto vlineto;
+      case 0x06: // hlineto
+         if (sp < 1) return STBTT__CSERR("hlineto stack");
+         for (;;) {
+            if (i >= sp) break;
+            csctx_rline_to(c, s[i], 0);
+            i++;
+      vlineto:
+            if (i >= sp) break;
+            csctx_rline_to(c, 0, s[i]);
+            i++;
+         }
+         break;
+
+      case 0x1F: // hvcurveto
+         if (sp < 4) return STBTT__CSERR("hvcurveto stack");
+         goto hvcurveto;
+      case 0x1E: // vhcurveto
+         if (sp < 4) return STBTT__CSERR("vhcurveto stack");
+         for (;;) {
+            if (i + 3 >= sp) break;
+            csctx_rccurve_to(c, 0, s[i], s[i+1], s[i+2], s[i+3], (sp - i == 5) ? s[i + 4] : 0.0f);
+            i += 4;
+      hvcurveto:
+            if (i + 3 >= sp) break;
+            csctx_rccurve_to(c, s[i], 0, s[i+1], s[i+2], (sp - i == 5) ? s[i+4] : 0.0f, s[i+3]);
+            i += 4;
+         }
+         break;
+
+      case 0x08: // rrcurveto
+         if (sp < 6) return STBTT__CSERR("rcurveline stack");
+         for (; i + 5 < sp; i += 6)
+            csctx_rccurve_to(c, s[i], s[i+1], s[i+2], s[i+3], s[i+4], s[i+5]);
+         break;
+
+      case 0x18: // rcurveline
+         if (sp < 8) return STBTT__CSERR("rcurveline stack");
+         for (; i + 5 < sp - 2; i += 6)
+            csctx_rccurve_to(c, s[i], s[i+1], s[i+2], s[i+3], s[i+4], s[i+5]);
+         if (i + 1 >= sp) return STBTT__CSERR("rcurveline stack");
+         csctx_rline_to(c, s[i], s[i+1]);
+         break;
+
+      case 0x19: // rlinecurve
+         if (sp < 8) return STBTT__CSERR("rlinecurve stack");
+         for (; i + 1 < sp - 6; i += 2)
+            csctx_rline_to(c, s[i], s[i+1]);
+         if (i + 5 >= sp) return STBTT__CSERR("rlinecurve stack");
+         csctx_rccurve_to(c, s[i], s[i+1], s[i+2], s[i+3], s[i+4], s[i+5]);
+         break;
+
+      case 0x1A: // vvcurveto
+      case 0x1B: // hhcurveto
+         if (sp < 4) return STBTT__CSERR("(vv|hh)curveto stack");
+         f = 0.0;
+         if (sp & 1) { f = s[i]; i++; }
+         for (; i + 3 < sp; i += 4) {
+            if (b0 == 0x1B)
+               csctx_rccurve_to(c, s[i], f, s[i+1], s[i+2], s[i+3], 0.0);
+            else
+               csctx_rccurve_to(c, f, s[i], s[i+1], s[i+2], 0.0, s[i+3]);
+            f = 0.0;
+         }
+         break;
+
+      case 0x0A: // callsubr
+         if (!has_subrs) {
+            if (info->fdselect.size)
+               subrs = cid_get_glyph_subrs(info, glyph_index);
+            has_subrs = 1;
+         }
+         // fallthrough
+      case 0x1D: // callgsubr
+         if (sp < 1) return STBTT__CSERR("call(g|)subr stack");
+         v = (int) s[--sp];
+         if (subr_stack_height >= 10) return STBTT__CSERR("recursion limit");
+         subr_stack[subr_stack_height++] = b;
+         b = get_subr(b0 == 0x0A ? subrs : info->gsubrs, v);
+         if (b.size == 0) return STBTT__CSERR("subr not found");
+         b.cursor = 0;
+         clear_stack = 0;
+         break;
+
+      case 0x0B: // return
+         if (subr_stack_height <= 0) return STBTT__CSERR("return outside subr");
+         b = subr_stack[--subr_stack_height];
+         clear_stack = 0;
+         break;
+
+      case 0x0E: // endchar
+         csctx_close_shape(c);
+         return 1;
+
+      case 0x0C: { // two-byte escape
+         float dx1, dx2, dx3, dx4, dx5, dx6, dy1, dy2, dy3, dy4, dy5, dy6;
+         float dx, dy;
+         int b1 = getbyte(&b);
+         switch (b1) {
+         // @TODO These "flex" implementations ignore the flex-depth and resolution,
+         // and always draw beziers.
+         case 0x22: // hflex
+            if (sp < 7) return STBTT__CSERR("hflex stack");
+            dx1 = s[0];
+            dx2 = s[1];
+            dy2 = s[2];
+            dx3 = s[3];
+            dx4 = s[4];
+            dx5 = s[5];
+            dx6 = s[6];
+            csctx_rccurve_to(c, dx1, 0, dx2, dy2, dx3, 0);
+            csctx_rccurve_to(c, dx4, 0, dx5, -dy2, dx6, 0);
+            break;
+
+         case 0x23: // flex
+            if (sp < 13) return STBTT__CSERR("flex stack");
+            dx1 = s[0];
+            dy1 = s[1];
+            dx2 = s[2];
+            dy2 = s[3];
+            dx3 = s[4];
+            dy3 = s[5];
+            dx4 = s[6];
+            dy4 = s[7];
+            dx5 = s[8];
+            dy5 = s[9];
+            dx6 = s[10];
+            dy6 = s[11];
+            //fd is s[12]
+            csctx_rccurve_to(c, dx1, dy1, dx2, dy2, dx3, dy3);
+            csctx_rccurve_to(c, dx4, dy4, dx5, dy5, dx6, dy6);
+            break;
+
+         case 0x24: // hflex1
+            if (sp < 9) return STBTT__CSERR("hflex1 stack");
+            dx1 = s[0];
+            dy1 = s[1];
+            dx2 = s[2];
+            dy2 = s[3];
+            dx3 = s[4];
+            dx4 = s[5];
+            dx5 = s[6];
+            dy5 = s[7];
+            dx6 = s[8];
+            csctx_rccurve_to(c, dx1, dy1, dx2, dy2, dx3, 0);
+            csctx_rccurve_to(c, dx4, 0, dx5, dy5, dx6, -(dy1+dy2+dy5));
+            break;
+
+         case 0x25: // flex1
+            if (sp < 11) return STBTT__CSERR("flex1 stack");
+            dx1 = s[0];
+            dy1 = s[1];
+            dx2 = s[2];
+            dy2 = s[3];
+            dx3 = s[4];
+            dy3 = s[5];
+            dx4 = s[6];
+            dy4 = s[7];
+            dx5 = s[8];
+            dy5 = s[9];
+            dx6 = dy6 = s[10];
+            dx = dx1+dx2+dx3+dx4+dx5;
+            dy = dy1+dy2+dy3+dy4+dy5;
+            if (fabs(dx) > fabs(dy))
+               dy6 = -dy;
+            else
+               dx6 = -dx;
+            csctx_rccurve_to(c, dx1, dy1, dx2, dy2, dx3, dy3);
+            csctx_rccurve_to(c, dx4, dy4, dx5, dy5, dx6, dy6);
+            break;
+
+         default:
+            return STBTT__CSERR("unimplemented");
+         }
+      } break;
+
+      default:
+         if (b0 != 255 && b0 != 28 && (b0 < 32 || b0 > 254))
+            return STBTT__CSERR("reserved operator");
+
+         // push immediate
+         if (b0 == 255) {
+            f = (float)(int32)getint(&b) / 0x10000;
+         } else {
+            skip(&b, -1);
+            f = (float)(short)cff_int(&b);
+         }
+         if (sp >= 48) return STBTT__CSERR("push stack overflow");
+         s[sp++] = f;
+         clear_stack = 0;
+         break;
+      }
+      if (clear_stack) sp = 0;
+   }
+   return STBTT__CSERR("no endchar");
+
+#undef STBTT__CSERR
+}
+
+static int glyph_shape_t2(font·Info *info, int glyph_index, font·Vertex **pvertices)
+{
+   // runs the charstring twice, once to count and once to output (to avoid realloc)
+   csctx count_ctx = CSCTX_INIT(1);
+   csctx output_ctx = CSCTX_INIT(0);
+   if (run_charstring(info, glyph_index, &count_ctx)) {
+      *pvertices = malloc(count_ctx.num_vertices*sizeof(font·Vertex));
+      output_ctx.pvertices = *pvertices;
+      if (run_charstring(info, glyph_index, &output_ctx)) {
+         assert(output_ctx.num_vertices == count_ctx.num_vertices);
+         return output_ctx.num_vertices;
+      }
+   }
+   *pvertices = nil;
+   return 0;
+}
+
+static 
+int 
+glyph_info_t2(font·Info *info, int glyph_index, int *x0, int *y0, int *x1, int *y1)
+{
+   csctx c = CSCTX_INIT(1);
+   int r = run_charstring(info, glyph_index, &c);
+   if (x0)  *x0 = r ? c.min_x : 0;
+   if (y0)  *y0 = r ? c.min_y : 0;
+   if (x1)  *x1 = r ? c.max_x : 0;
+   if (y1)  *y1 = r ? c.max_y : 0;
+   return r ? c.num_vertices : 0;
+}
+
+int 
+font·glyph_shape(font·Info *info, int glyph_index, font·Vertex **pvertices)
+{
+   if (!info->cff.size)
+      return glyph_shape_tt(info, glyph_index, pvertices);
+   else
+      return glyph_shape_t2(info, glyph_index, pvertices);
+}
+
+void 
+font·glyph_hmetrics(font·Info *info, int glyph_index, int *advanceWidth, int *leftSideBearing)
+{
+   ushort numOfLongHorMetrics = ttUSHORT(info->data+info->hhea + 34);
+   if (glyph_index < numOfLongHorMetrics) {
+      if (advanceWidth)     *advanceWidth    = ttSHORT(info->data + info->hmtx + 4*glyph_index);
+      if (leftSideBearing)  *leftSideBearing = ttSHORT(info->data + info->hmtx + 4*glyph_index + 2);
+   } else {
+      if (advanceWidth)     *advanceWidth    = ttSHORT(info->data + info->hmtx + 4*(numOfLongHorMetrics-1));
+      if (leftSideBearing)  *leftSideBearing = ttSHORT(info->data + info->hmtx + 4*numOfLongHorMetrics + 2*(glyph_index - numOfLongHorMetrics));
+   }
+}
+
+int 
+font·kerntablen(font·Info *info)
+{
+   uchar *data = info->data + info->kern;
+
+   // we only look at the first table. it must be 'horizontal' and format 0.
+   if (!info->kern)
+      return 0;
+   if (ttUSHORT(data+2) < 1) // number of tables, need at least 1
+      return 0;
+   if (ttUSHORT(data+8) != 1) // horizontal flag must be set in format
+      return 0;
+
+   return ttUSHORT(data+10);
+}
+
+int 
+font·kerntab(font·Info *info, font·TabElt* table, int table_length)
+{
+   uchar *data = info->data + info->kern;
+   int k, length;
+
+   // we only look at the first table. it must be 'horizontal' and format 0.
+   if (!info->kern)
+      return 0;
+   if (ttUSHORT(data+2) < 1) // number of tables, need at least 1
+      return 0;
+   if (ttUSHORT(data+8) != 1) // horizontal flag must be set in format
+      return 0;
+
+   length = ttUSHORT(data+10);
+   if (table_length < length)
+      length = table_length;
+
+   for (k = 0; k < length; k++)
+   {
+      table[k].glyph1 = ttUSHORT(data+18+(k*6));
+      table[k].glyph2 = ttUSHORT(data+20+(k*6));
+      table[k].advance = ttSHORT(data+22+(k*6));
+   }
+
+   return length;
+}
+
+static 
+int  
+glyph_kernadvance(const font·Info *info, int glyph1, int glyph2)
+{
+   uchar *data = info->data + info->kern;
+   uint32 needle, straw;
+   int l, r, m;
+
+   // we only look at the first table. it must be 'horizontal' and format 0.
+   if (!info->kern)
+      return 0;
+   if (ttUSHORT(data+2) < 1) // number of tables, need at least 1
+      return 0;
+   if (ttUSHORT(data+8) != 1) // horizontal flag must be set in format
+      return 0;
+
+   l = 0;
+   r = ttUSHORT(data+10) - 1;
+   needle = glyph1 << 16 | glyph2;
+   while (l <= r) {
+      m = (l + r) >> 1;
+      straw = ttULONG(data+18+(m*6)); // note: unaligned read
+      if (needle < straw)
+         r = m - 1;
+      else if (needle > straw)
+         l = m + 1;
+      else
+         return ttSHORT(data+22+(m*6));
+   }
+   return 0;
+}
+
+static 
+int32  
+coverage_index(uchar *coverageTable, int glyph)
+{
+    ushort coverageFormat = ttUSHORT(coverageTable);
+    switch(coverageFormat) {
+        case 1: {
+            ushort glyphCount = ttUSHORT(coverageTable + 2);
+
+            // Binary search.
+            int32 l=0, r=glyphCount-1, m;
+            int straw, needle=glyph;
+            while (l <= r) {
+                uchar *glyphArray = coverageTable + 4;
+                ushort glyphID;
+                m = (l + r) >> 1;
+                glyphID = ttUSHORT(glyphArray + 2 * m);
+                straw = glyphID;
+                if (needle < straw)
+                    r = m - 1;
+                else if (needle > straw)
+                    l = m + 1;
+                else {
+                     return m;
+                }
+            }
+        } break;
+
+        case 2: {
+            ushort rangeCount = ttUSHORT(coverageTable + 2);
+            uchar *rangeArray = coverageTable + 4;
+
+            // Binary search.
+            int32 l=0, r=rangeCount-1, m;
+            int strawStart, strawEnd, needle=glyph;
+            while (l <= r) {
+                uchar *rangeRecord;
+                m = (l + r) >> 1;
+                rangeRecord = rangeArray + 6 * m;
+                strawStart = ttUSHORT(rangeRecord);
+                strawEnd = ttUSHORT(rangeRecord + 2);
+                if (needle < strawStart)
+                    r = m - 1;
+                else if (needle > strawEnd)
+                    l = m + 1;
+                else {
+                    ushort startCoverageIndex = ttUSHORT(rangeRecord + 4);
+                    return startCoverageIndex + glyph - strawStart;
+                }
+            }
+        } break;
+
+        default: {
+            // There are no other cases.
+            assert(0);
+        } break;
+    }
+
+    return -1;
+}
+
+static 
+int32  
+glyph_class(uchar *classDefTable, int glyph)
+{
+    ushort classDefFormat = ttUSHORT(classDefTable);
+    switch(classDefFormat)
+    {
+        case 1: {
+            ushort startGlyphID = ttUSHORT(classDefTable + 2);
+            ushort glyphCount = ttUSHORT(classDefTable + 4);
+            uchar *classDef1ValueArray = classDefTable + 6;
+
+            if (glyph >= startGlyphID && glyph < startGlyphID + glyphCount)
+                return (int32)ttUSHORT(classDef1ValueArray + 2 * (glyph - startGlyphID));
+
+            classDefTable = classDef1ValueArray + 2 * glyphCount;
+        } break;
+
+        case 2: {
+            ushort classRangeCount = ttUSHORT(classDefTable + 2);
+            uchar *classRangeRecords = classDefTable + 4;
+
+            // Binary search.
+            int32 l=0, r=classRangeCount-1, m;
+            int strawStart, strawEnd, needle=glyph;
+            while (l <= r) {
+                uchar *classRangeRecord;
+                m = (l + r) >> 1;
+                classRangeRecord = classRangeRecords + 6 * m;
+                strawStart = ttUSHORT(classRangeRecord);
+                strawEnd = ttUSHORT(classRangeRecord + 2);
+                if (needle < strawStart)
+                    r = m - 1;
+                else if (needle > strawEnd)
+                    l = m + 1;
+                else
+                    return (int32)ttUSHORT(classRangeRecord + 4);
+            }
+
+            classDefTable = classRangeRecords + 6 * classRangeCount;
+        } break;
+
+        default: {
+            // There are no other cases.
+            assert(0);
+        } break;
+    }
+
+    return -1;
+}
+
+static 
+int32  
+glyph_gposadvance(const font·Info *info, int glyph1, int glyph2)
+{
+    ushort lookupListOffset;
+    uchar *lookupList;
+    ushort lookupCount;
+    uchar *data;
+    int32 i;
+
+    if (!info->gpos) return 0;
+
+    data = info->data + info->gpos;
+
+    if (ttUSHORT(data+0) != 1) return 0; // Major version 1
+    if (ttUSHORT(data+2) != 0) return 0; // Minor version 0
+
+    lookupListOffset = ttUSHORT(data+8);
+    lookupList = data + lookupListOffset;
+    lookupCount = ttUSHORT(lookupList);
+
+    for (i=0; i<lookupCount; ++i) {
+        ushort lookupOffset = ttUSHORT(lookupList + 2 + 2 * i);
+        uchar *lookupTable = lookupList + lookupOffset;
+
+        ushort lookupType = ttUSHORT(lookupTable);
+        ushort subTableCount = ttUSHORT(lookupTable + 4);
+        uchar *subTableOffsets = lookupTable + 6;
+        switch(lookupType) {
+            case 2: { // Pair Adjustment Positioning Subtable
+                int32 sti;
+                for (sti=0; sti<subTableCount; sti++) {
+                    ushort subtableOffset = ttUSHORT(subTableOffsets + 2 * sti);
+                    uchar *table = lookupTable + subtableOffset;
+                    ushort posFormat = ttUSHORT(table);
+                    ushort coverageOffset = ttUSHORT(table + 2);
+                    int32 coverageIndex = coverage_index(table + coverageOffset, glyph1);
+                    if (coverageIndex == -1) continue;
+
+                    switch (posFormat) {
+                        case 1: {
+                            int32 l, r, m;
+                            int straw, needle;
+                            ushort valueFormat1 = ttUSHORT(table + 4);
+                            ushort valueFormat2 = ttUSHORT(table + 6);
+                            int32 valueRecordPairSizeInBytes = 2;
+                            ushort pairSetCount = ttUSHORT(table + 8);
+                            ushort pairPosOffset = ttUSHORT(table + 10 + 2 * coverageIndex);
+                            uchar *pairValueTable = table + pairPosOffset;
+                            ushort pairValueCount = ttUSHORT(pairValueTable);
+                            uchar *pairValueArray = pairValueTable + 2;
+                            // TODO: Support more formats.
+                            if (valueFormat1 != 4) return 0;
+                            if (valueFormat2 != 0) return 0;
+
+                            assert(coverageIndex < pairSetCount);
+
+                            needle=glyph2;
+                            r=pairValueCount-1;
+                            l=0;
+
+                            // Binary search.
+                            while (l <= r) {
+                                ushort secondGlyph;
+                                uchar *pairValue;
+                                m = (l + r) >> 1;
+                                pairValue = pairValueArray + (2 + valueRecordPairSizeInBytes) * m;
+                                secondGlyph = ttUSHORT(pairValue);
+                                straw = secondGlyph;
+                                if (needle < straw)
+                                    r = m - 1;
+                                else if (needle > straw)
+                                    l = m + 1;
+                                else {
+                                    short xAdvance = ttSHORT(pairValue + 2);
+                                    return xAdvance;
+                                }
+                            }
+                        } break;
+
+                        case 2: {
+                            ushort valueFormat1 = ttUSHORT(table + 4);
+                            ushort valueFormat2 = ttUSHORT(table + 6);
+
+                            ushort classDef1Offset = ttUSHORT(table + 8);
+                            ushort classDef2Offset = ttUSHORT(table + 10);
+                            int glyph1class = glyph_class(table + classDef1Offset, glyph1);
+                            int glyph2class = glyph_class(table + classDef2Offset, glyph2);
+
+                            ushort class1Count = ttUSHORT(table + 12);
+                            ushort class2Count = ttUSHORT(table + 14);
+                            assert(glyph1class < class1Count);
+                            assert(glyph2class < class2Count);
+
+                            // TODO: Support more formats.
+                            if (valueFormat1 != 4) return 0;
+                            if (valueFormat2 != 0) return 0;
+
+                            if (glyph1class >= 0 && glyph1class < class1Count && glyph2class >= 0 && glyph2class < class2Count) {
+                                uchar *class1Records = table + 16;
+                                uchar *class2Records = class1Records + 2 * (glyph1class * class2Count);
+                                short xAdvance = ttSHORT(class2Records + 2 * glyph2class);
+                                return xAdvance;
+                            }
+                        } break;
+
+                        default: {
+                            // There are no other cases.
+                            assert(0);
+                            break;
+                        };
+                    }
+                }
+                break;
+            };
+
+            default:
+                // TODO: Implement other stuff.
+                break;
+        }
+    }
+
+    return 0;
+}
+
+int  
+font·glyph_kernadvance(font·Info *info, int g1, int g2)
+{
+   int xAdvance = 0;
+
+   if (info->gpos)
+      xAdvance += glyph_gposadvance(info, g1, g2);
+   else if (info->kern)
+      xAdvance += glyph_kernadvance(info, g1, g2);
+
+   return xAdvance;
+}
+
+int  
+font·code_kernadvance(font·Info *info, int ch1, int ch2)
+{
+   if (!info->kern && !info->gpos) // if no kerning table, don't waste time looking up both codepoint->glyphs
+      return 0;
+   return font·glyph_kernadvance(info, font·glyph_index(info,ch1), font·glyph_index(info,ch2));
+}
+
+void 
+font·code_hmetrics(font·Info *info, int codepoint, int *advanceWidth, int *lsb)
+{
+   font·glyph_hmetrics(info, font·glyph_index(info,codepoint), advanceWidth, lsb);
+}
+
+void 
+font·vmetrics(font·Info *info, int *ascent, int *descent, int *lineGap)
+{
+   if (ascent ) *ascent  = ttSHORT(info->data+info->hhea + 4);
+   if (descent) *descent = ttSHORT(info->data+info->hhea + 6);
+   if (lineGap) *lineGap = ttSHORT(info->data+info->hhea + 8);
+}
+
+void 
+font·bbox(font·Info *info, int *x0, int *y0, int *x1, int *y1)
+{
+   *x0 = ttSHORT(info->data + info->head + 36);
+   *y0 = ttSHORT(info->data + info->head + 38);
+   *x1 = ttSHORT(info->data + info->head + 40);
+   *y1 = ttSHORT(info->data + info->head + 42);
+}
+
+float 
+font·scaleheightto(font·Info *info, float height)
+{
+   int fheight = ttSHORT(info->data + info->hhea + 4) - ttSHORT(info->data + info->hhea + 6);
+   return (float) height / fheight;
+}
+
+float 
+font·scaleheighttoem(font·Info *info, float pixels)
+{
+   int unitsPerEm = ttUSHORT(info->data + info->head + 18);
+   return pixels / unitsPerEm;
+}
+
+void 
+font·freeshape(font·Info *info, font·Vertex *v)
+{
+   free(v);
+}
+
+static 
+uchar *
+find_svg(const font·Info *info, int gl)
+{
+   int i;
+   uchar *data = info->data;
+   uchar *svg_doc_list = data + get_svg((font·Info *) info);
+
+   int numEntries = ttUSHORT(svg_doc_list);
+   uchar *svg_docs = svg_doc_list + 2;
+
+   for(i=0; i<numEntries; i++) {
+      uchar *svg_doc = svg_docs + (12 * i);
+      if ((gl >= ttUSHORT(svg_doc)) && (gl <= ttUSHORT(svg_doc + 2)))
+         return svg_doc;
+   }
+   return 0;
+}
+
+int 
+font·glyph_svg(font·Info *info, int gl, char **svg)
+{
+   uchar *data = info->data;
+   uchar *svg_doc;
+
+   if (info->svg == 0)
+      return 0;
+
+   svg_doc = find_svg(info, gl);
+   if (svg_doc != nil) {
+      *svg = (char *) data + info->svg + ttULONG(svg_doc + 4);
+      return ttULONG(svg_doc + 8);
+   } else {
+      return 0;
+   }
+}
+
+int 
+font·code_svg(font·Info *info, int unicode_codepoint, char **svg)
+{
+   return font·glyph_svg(info, font·glyph_index(info, unicode_codepoint), svg);
+}
+
+// -----------------------------------------------------------------------
+// antialiasing software rasterizer
+
+void 
+font·glyph_bitmapbox_subpixel(font·Info *font, int glyph, float scale_x, float scale_y,float shift_x, float shift_y, int *ix0, int *iy0, int *ix1, int *iy1)
+{
+   int x0=0,y0=0,x1,y1; // =0 suppresses compiler warning
+   if (!font·glyph_box(font, glyph, &x0,&y0,&x1,&y1)) {
+      // e.g. space character
+      if (ix0) *ix0 = 0;
+      if (iy0) *iy0 = 0;
+      if (ix1) *ix1 = 0;
+      if (iy1) *iy1 = 0;
+   } else {
+      // move to integral bboxes (treating pixels as little squares, what pixels get touched)?
+      if (ix0) *ix0 = (int)floor( x0 * scale_x + shift_x);
+      if (iy0) *iy0 = (int)floor(-y1 * scale_y + shift_y);
+      if (ix1) *ix1 = (int)ceil( x1 * scale_x + shift_x);
+      if (iy1) *iy1 = (int)ceil(-y0 * scale_y + shift_y);
+   }
+}
+
+void 
+font·glyph_bitmapbox(font·Info *font, int glyph, float scale_x, float scale_y, int *ix0, int *iy0, int *ix1, int *iy1)
+{
+   font·glyph_bitmapbox_subpixel(font, glyph, scale_x, scale_y,0.0f,0.0f, ix0, iy0, ix1, iy1);
+}
+
+void 
+font·code_bitmapbox_subpixel(font·Info *font, int codepoint, float scale_x, float scale_y, float shift_x, float shift_y, int *ix0, int *iy0, int *ix1, int *iy1)
+{
+   font·glyph_bitmapbox_subpixel(font, font·glyph_index(font,codepoint), scale_x, scale_y,shift_x,shift_y, ix0,iy0,ix1,iy1);
+}
+
+void 
+font·code_bitmapbox(font·Info *font, int codepoint, float scale_x, float scale_y, int *ix0, int *iy0, int *ix1, int *iy1)
+{
+   font·code_bitmapbox_subpixel(font, codepoint, scale_x, scale_y,0.0f,0.0f, ix0,iy0,ix1,iy1);
+}
+
+// ------------------------------------------------------------------------
+//  Rasterizer
+
+typedef struct hheap_chunk
+{
+   struct hheap_chunk *next;
+} hheap_chunk;
+
+typedef struct hheap
+{
+   struct hheap_chunk *head;
+   void   *first_free;
+   int    num_remaining_in_head_chunk;
+} hheap;
+
+static 
+void *
+hheap_alloc(hheap *hh, size_t size, void *userdata)
+{
+   if (hh->first_free) {
+      void *p = hh->first_free;
+      hh->first_free = * (void **) p;
+      return p;
+   } else {
+      if (hh->num_remaining_in_head_chunk == 0) {
+         int count = (size < 32 ? 2000 : size < 128 ? 800 : 100);
+         hheap_chunk *c = malloc(sizeof(hheap_chunk) + size * count);
+         if (c == nil)
+            return nil;
+         c->next = hh->head;
+         hh->head = c;
+         hh->num_remaining_in_head_chunk = count;
+      }
+      --hh->num_remaining_in_head_chunk;
+      return (char *) (hh->head) + sizeof(hheap_chunk) + size * hh->num_remaining_in_head_chunk;
+   }
+}
+
+static 
+void 
+hheap_free(hheap *hh, void *p)
+{
+   *(void **) p = hh->first_free;
+   hh->first_free = p;
+}
+
+static 
+void 
+hheap_cleanup(hheap *hh, void *userdata)
+{
+   hheap_chunk *c = hh->head;
+   while (c) {
+      hheap_chunk *n = c->next;
+      free(c);
+      c = n;
+   }
+}
+
+static 
+ActiveEdge *
+new_active(hheap *hh, Edge *e, int off_x, float start_point, void *userdata)
+{
+   ActiveEdge *z = (ActiveEdge *) hheap_alloc(hh, sizeof(*z), userdata);
+   float dxdy = (e->x1 - e->x0) / (e->y1 - e->y0);
+   assert(z != nil);
+   //assert(e->y0 <= start_point);
+   if (!z) return z;
+   z->fdx = dxdy;
+   z->fdy = dxdy != 0.0f ? (1.0f/dxdy) : 0.0f;
+   z->fx = e->x0 + dxdy * (start_point - e->y0);
+   z->fx -= off_x;
+   z->direction = e->invert ? 1.0f : -1.0f;
+   z->sy = e->y0;
+   z->ey = e->y1;
+   z->next = 0;
+   return z;
+}
+
+// the edge passed in here does not cross the vertical line at x or the vertical line at x+1
+// (i.e. it has already been clipped to those)
+static 
+void 
+handle_clipped_edge(float *scanline, int x, ActiveEdge *e, float x0, float y0, float x1, float y1)
+{
+   if (y0 == y1) return;
+   assert(y0 < y1);
+   assert(e->sy <= e->ey);
+   if (y0 > e->ey) return;
+   if (y1 < e->sy) return;
+   if (y0 < e->sy) {
+      x0 += (x1-x0) * (e->sy - y0) / (y1-y0);
+      y0 = e->sy;
+   }
+   if (y1 > e->ey) {
+      x1 += (x1-x0) * (e->ey - y1) / (y1-y0);
+      y1 = e->ey;
+   }
+
+   if (x0 == x)
+      assert(x1 <= x+1);
+   else if (x0 == x+1)
+      assert(x1 >= x);
+   else if (x0 <= x)
+      assert(x1 <= x);
+   else if (x0 >= x+1)
+      assert(x1 >= x+1);
+   else
+      assert(x1 >= x && x1 <= x+1);
+
+   if (x0 <= x && x1 <= x)
+      scanline[x] += e->direction * (y1-y0);
+   else if (x0 >= x+1 && x1 >= x+1)
+      ;
+   else {
+      assert(x0 >= x && x0 <= x+1 && x1 >= x && x1 <= x+1);
+      scanline[x] += e->direction * (y1-y0) * (1-((x0-x)+(x1-x))/2); // coverage = 1 - average x position
+   }
+}
+
+static 
+void 
+fill_active_edges_new(float *scanline, float *scanline_fill, int len, ActiveEdge *e, float y_top)
+{
+   float y_bottom = y_top+1;
+
+   while (e) {
+      // brute force every pixel
+
+      // compute intersection points with top & bottom
+      assert(e->ey >= y_top);
+
+      if (e->fdx == 0) {
+         float x0 = e->fx;
+         if (x0 < len) {
+            if (x0 >= 0) {
+               handle_clipped_edge(scanline,(int) x0,e, x0,y_top, x0,y_bottom);
+               handle_clipped_edge(scanline_fill-1,(int) x0+1,e, x0,y_top, x0,y_bottom);
+            } else {
+               handle_clipped_edge(scanline_fill-1,0,e, x0,y_top, x0,y_bottom);
+            }
+         }
+      } else {
+         float x0 = e->fx;
+         float dx = e->fdx;
+         float xb = x0 + dx;
+         float x_top, x_bottom;
+         float sy0,sy1;
+         float dy = e->fdy;
+         assert(e->sy <= y_bottom && e->ey >= y_top);
+
+         // compute endpoints of line segment clipped to this scanline (if the
+         // line segment starts on this scanline. x0 is the intersection of the
+         // line with y_top, but that may be off the line segment.
+         if (e->sy > y_top) {
+            x_top = x0 + dx * (e->sy - y_top);
+            sy0 = e->sy;
+         } else {
+            x_top = x0;
+            sy0 = y_top;
+         }
+         if (e->ey < y_bottom) {
+            x_bottom = x0 + dx * (e->ey - y_top);
+            sy1 = e->ey;
+         } else {
+            x_bottom = xb;
+            sy1 = y_bottom;
+         }
+
+         if (x_top >= 0 && x_bottom >= 0 && x_top < len && x_bottom < len) {
+            // from here on, we don't have to range check x values
+
+            if ((int) x_top == (int) x_bottom) {
+               float height;
+               // simple case, only spans one pixel
+               int x = (int) x_top;
+               height = sy1 - sy0;
+               assert(x >= 0 && x < len);
+               scanline[x] += e->direction * (1-((x_top - x) + (x_bottom-x))/2)  * height;
+               scanline_fill[x] += e->direction * height; // everything right of this pixel is filled
+            } else {
+               int x,x1,x2;
+               float y_crossing, step, sign, area;
+               // covers 2+ pixels
+               if (x_top > x_bottom) {
+                  // flip scanline vertically; signed area is the same
+                  float t;
+                  sy0 = y_bottom - (sy0 - y_top);
+                  sy1 = y_bottom - (sy1 - y_top);
+                  t = sy0, sy0 = sy1, sy1 = t;
+                  t = x_bottom, x_bottom = x_top, x_top = t;
+                  dx = -dx;
+                  dy = -dy;
+                  t = x0, x0 = xb, xb = t;
+               }
+
+               x1 = (int) x_top;
+               x2 = (int) x_bottom;
+               // compute intersection with y axis at x1+1
+               y_crossing = (x1+1 - x0) * dy + y_top;
+
+               sign = e->direction;
+               // area of the rectangle covered from y0..y_crossing
+               area = sign * (y_crossing-sy0);
+               // area of the triangle (x_top,y0), (x+1,y0), (x+1,y_crossing)
+               scanline[x1] += area * (1-((x_top - x1)+(x1+1-x1))/2);
+
+               step = sign * dy;
+               for (x = x1+1; x < x2; ++x) {
+                  scanline[x] += area + step/2;
+                  area += step;
+               }
+               y_crossing += dy * (x2 - (x1+1));
+
+               assert(fabs(area) <= 1.01f);
+
+               scanline[x2] += area + sign * (1-((x2-x2)+(x_bottom-x2))/2) * (sy1-y_crossing);
+
+               scanline_fill[x2] += sign * (sy1-sy0);
+            }
+         } else {
+            // if edge goes outside of box we're drawing, we require
+            // clipping logic. since this does not match the intended use
+            // of this library, we use a different, very slow brute
+            // force implementation
+            int x;
+            for (x=0; x < len; ++x) {
+               // cases:
+               //
+               // there can be up to two intersections with the pixel. any intersection
+               // with left or right edges can be handled by splitting into two (or three)
+               // regions. intersections with top & bottom do not necessitate case-wise logic.
+               //
+               // the old way of doing this found the intersections with the left & right edges,
+               // then used some simple logic to produce up to three segments in sorted order
+               // from top-to-bottom. however, this had a problem: if an x edge was epsilon
+               // across the x border, then the corresponding y position might not be distinct
+               // from the other y segment, and it might ignored as an empty segment. to avoid
+               // that, we need to explicitly produce segments based on x positions.
+
+               // rename variables to clearly-defined pairs
+               float y0 = y_top;
+               float x1 = (float) (x);
+               float x2 = (float) (x+1);
+               float x3 = xb;
+               float y3 = y_bottom;
+
+               // x = e->x + e->dx * (y-y_top)
+               // (y-y_top) = (x - e->x) / e->dx
+               // y = (x - e->x) / e->dx + y_top
+               float y1 = (x - x0) / dx + y_top;
+               float y2 = (x+1 - x0) / dx + y_top;
+
+               if (x0 < x1 && x3 > x2) {         // three segments descending down-right
+                  handle_clipped_edge(scanline,x,e, x0,y0, x1,y1);
+                  handle_clipped_edge(scanline,x,e, x1,y1, x2,y2);
+                  handle_clipped_edge(scanline,x,e, x2,y2, x3,y3);
+               } else if (x3 < x1 && x0 > x2) {  // three segments descending down-left
+                  handle_clipped_edge(scanline,x,e, x0,y0, x2,y2);
+                  handle_clipped_edge(scanline,x,e, x2,y2, x1,y1);
+                  handle_clipped_edge(scanline,x,e, x1,y1, x3,y3);
+               } else if (x0 < x1 && x3 > x1) {  // two segments across x, down-right
+                  handle_clipped_edge(scanline,x,e, x0,y0, x1,y1);
+                  handle_clipped_edge(scanline,x,e, x1,y1, x3,y3);
+               } else if (x3 < x1 && x0 > x1) {  // two segments across x, down-left
+                  handle_clipped_edge(scanline,x,e, x0,y0, x1,y1);
+                  handle_clipped_edge(scanline,x,e, x1,y1, x3,y3);
+               } else if (x0 < x2 && x3 > x2) {  // two segments across x+1, down-right
+                  handle_clipped_edge(scanline,x,e, x0,y0, x2,y2);
+                  handle_clipped_edge(scanline,x,e, x2,y2, x3,y3);
+               } else if (x3 < x2 && x0 > x2) {  // two segments across x+1, down-left
+                  handle_clipped_edge(scanline,x,e, x0,y0, x2,y2);
+                  handle_clipped_edge(scanline,x,e, x2,y2, x3,y3);
+               } else {  // one segment
+                  handle_clipped_edge(scanline,x,e, x0,y0, x3,y3);
+               }
+            }
+         }
+      }
+      e = e->next;
+   }
+}
+
+// directly AA rasterize edges w/o supersampling
+static 
+void 
+rasterize_sorted_edges(font·Bitmap *result, Edge *e, int n, int vsubsample, int off_x, int off_y, void *userdata)
+{
+   hheap hh = { 0, 0, 0 };
+   ActiveEdge *active = nil;
+   int y,j=0, i;
+   float scanline_data[129], *scanline, *scanline2;
+
+   if (result->w > 64)
+      scanline = malloc((result->w*2+1) * sizeof(float));
+   else
+      scanline = scanline_data;
+
+   scanline2 = scanline + result->w;
+
+   y = off_y;
+   e[n].y0 = (float) (off_y + result->h) + 1;
+
+   while (j < result->h) {
+      // find center of pixel for this scanline
+      float scan_y_top    = y + 0.0f;
+      float scan_y_bottom = y + 1.0f;
+      ActiveEdge **step = &active;
+
+      memset(scanline , 0, result->w*sizeof(scanline[0]));
+      memset(scanline2, 0, (result->w+1)*sizeof(scanline[0]));
+
+      // update all active edges;
+      // remove all active edges that terminate before the top of this scanline
+      while (*step) {
+         ActiveEdge * z = *step;
+         if (z->ey <= scan_y_top) {
+            *step = z->next; // delete from list
+            assert(z->direction);
+            z->direction = 0;
+            hheap_free(&hh, z);
+         } else {
+            step = &((*step)->next); // advance through list
+         }
+      }
+
+      // insert all edges that start before the bottom of this scanline
+      while (e->y0 <= scan_y_bottom) {
+         if (e->y0 != e->y1) {
+            ActiveEdge *z = new_active(&hh, e, off_x, scan_y_top, userdata);
+            if (z != nil) {
+               if (j == 0 && off_y != 0) {
+                  if (z->ey < scan_y_top) {
+                     // this can happen due to subpixel positioning and some kind of fp rounding error i think
+                     z->ey = scan_y_top;
+                  }
+               }
+               assert(z->ey >= scan_y_top); // if we get really unlucky a tiny bit of an edge can be out of bounds
+               // insert at front
+               z->next = active;
+               active = z;
+            }
+         }
+         ++e;
+      }
+
+      // now process all active edges
+      if (active)
+         fill_active_edges_new(scanline, scanline2+1, result->w, active, scan_y_top);
+
+      {
+         float sum = 0;
+         for (i=0; i < result->w; ++i) {
+            float k;
+            int m;
+            sum += scanline2[i];
+            k = scanline[i] + sum;
+            k = (float) fabs(k)*255 + 0.5f;
+            m = (int) k;
+            if (m > 255) m = 255;
+            result->pixels[j*result->stride + i] = (uchar) m;
+         }
+      }
+      // advance all the edges
+      step = &active;
+      while (*step) {
+         ActiveEdge *z = *step;
+         z->fx += z->fdx; // advance to position for current scanline
+         step = &((*step)->next); // advance through list
+      }
+
+      ++y;
+      ++j;
+   }
+
+   hheap_cleanup(&hh, userdata);
+
+   if (scanline != scanline_data)
+      free(scanline);
+}
+
+#define CMP_Y0(a,b)  ((a)->y0 < (b)->y0)
+
+static 
+void 
+sort_edges_ins_sort(Edge *p, int n)
+{
+   int i,j;
+   for (i=1; i < n; ++i) {
+      Edge t = p[i], *a = &t;
+      j = i;
+      while (j > 0) {
+         Edge *b = &p[j-1];
+         int c = CMP_Y0(a,b);
+         if (!c) break;
+         p[j] = p[j-1];
+         --j;
+      }
+      if (i != j)
+         p[j] = t;
+   }
+}
+
+static 
+void 
+sort_edges_quicksort(Edge *p, int n)
+{
+   /* threshold for transitioning to insertion sort */
+   while (n > 12) {
+      Edge t;
+      int c01,c12,c,m,i,j;
+
+      /* compute median of three */
+      m = n >> 1;
+      c01 = CMP_Y0(&p[0],&p[m]);
+      c12 = CMP_Y0(&p[m],&p[n-1]);
+      /* if 0 >= mid >= end, or 0 < mid < end, then use mid */
+      if (c01 != c12) {
+         /* otherwise, we'll need to swap something else to middle */
+         int z;
+         c = CMP_Y0(&p[0],&p[n-1]);
+         /* 0>mid && mid<n:  0>n => n; 0<n => 0 */
+         /* 0<mid && mid>n:  0>n => 0; 0<n => n */
+         z = (c == c12) ? 0 : n-1;
+         t = p[z];
+         p[z] = p[m];
+         p[m] = t;
+      }
+      /* now p[m] is the median-of-three */
+      /* swap it to the beginning so it won't move around */
+      t = p[0];
+      p[0] = p[m];
+      p[m] = t;
+
+      /* partition loop */
+      i=1;
+      j=n-1;
+      for(;;) {
+         /* handling of equality is crucial here */
+         /* for sentinels & efficiency with duplicates */
+         for (;;++i) {
+            if (!CMP_Y0(&p[i], &p[0])) break;
+         }
+         for (;;--j) {
+            if (!CMP_Y0(&p[0], &p[j])) break;
+         }
+         /* make sure we haven't crossed */
+         if (i >= j) break;
+         t = p[i];
+         p[i] = p[j];
+         p[j] = t;
+
+         ++i;
+         --j;
+      }
+      /* recurse on smaller side, iterate on larger */
+      if (j < (n-i)) {
+         sort_edges_quicksort(p,j);
+         p = p+i;
+         n = n-i;
+      } else {
+         sort_edges_quicksort(p+i, n-i);
+         n = j;
+      }
+   }
+}
+
+static 
+void 
+sort_edges(Edge *p, int n)
+{
+   sort_edges_quicksort(p, n);
+   sort_edges_ins_sort(p, n);
+}
+
+static 
+void 
+rasterize(font·Bitmap *result, Point *pts, int *wcount, int windings, float scale_x, float scale_y, float shift_x, float shift_y, int off_x, int off_y, int invert, void *userdata)
+{
+   float y_scale_inv = invert ? -scale_y : scale_y;
+   Edge *e;
+   int n,i,j,k,m;
+   int vsubsample = 1;
+   // vsubsample should divide 255 evenly; otherwise we won't reach full opacity
+
+   // now we have to blow out the windings into explicit edge lists
+   n = 0;
+   for (i=0; i < windings; ++i)
+      n += wcount[i];
+
+   e = malloc(sizeof(*e) * (n+1)); // add an extra one as a sentinel
+   if (e == 0) return;
+   n = 0;
+
+   m=0;
+   for (i=0; i < windings; ++i) {
+      Point *p = pts + m;
+      m += wcount[i];
+      j = wcount[i]-1;
+      for (k=0; k < wcount[i]; j=k++) {
+         int a=k,b=j;
+         // skip the Edge if horizontal
+         if (p[j].y == p[k].y)
+            continue;
+         // add edge from j to k to the list
+         e[n].invert = 0;
+         if (invert ? p[j].y > p[k].y : p[j].y < p[k].y) {
+            e[n].invert = 1;
+            a=j,b=k;
+         }
+         e[n].x0 = p[a].x * scale_x + shift_x;
+         e[n].y0 = (p[a].y * y_scale_inv + shift_y) * vsubsample;
+         e[n].x1 = p[b].x * scale_x + shift_x;
+         e[n].y1 = (p[b].y * y_scale_inv + shift_y) * vsubsample;
+         ++n;
+      }
+   }
+
+   // now sort the edges by their highest point (should snap to integer, and then by x)
+   //STBTT_sort(e, n, sizeof(e[0]), edge_compare);
+   sort_edges(e, n);
+
+   // now, traverse the scanlines and find the intersections on each scanline, use xor winding rule
+   rasterize_sorted_edges(result, e, n, vsubsample, off_x, off_y, userdata);
+
+   free(e);
+}
+
+static 
+void 
+add_point(Point *points, int n, float x, float y)
+{
+   if (!points) return; // during first pass, it's unallocated
+   points[n].x = x;
+   points[n].y = y;
+}
+
+// tessellate until threshold p is happy... @TODO warped to compensate for non-linear stretching
+static 
+int 
+tesselate_curve(Point *points, int *num_points, float x0, float y0, float x1, float y1, float x2, float y2, float objspace_flatness_squared, int n)
+{
+   // midpoint
+   float mx = (x0 + 2*x1 + x2)/4;
+   float my = (y0 + 2*y1 + y2)/4;
+   // versus directly drawn line
+   float dx = (x0+x2)/2 - mx;
+   float dy = (y0+y2)/2 - my;
+   if (n > 16) // 65536 segments on one curve better be enough!
+      return 1;
+   if (dx*dx+dy*dy > objspace_flatness_squared) { // half-pixel error allowed... need to be smaller if AA
+      tesselate_curve(points, num_points, x0,y0, (x0+x1)/2.0f,(y0+y1)/2.0f, mx,my, objspace_flatness_squared,n+1);
+      tesselate_curve(points, num_points, mx,my, (x1+x2)/2.0f,(y1+y2)/2.0f, x2,y2, objspace_flatness_squared,n+1);
+   } else {
+      add_point(points, *num_points,x2,y2);
+      *num_points = *num_points+1;
+   }
+   return 1;
+}
+
+static 
+void 
+tesselate_cubic(Point *points, int *num_points, float x0, float y0, float x1, float y1, float x2, float y2, float x3, float y3, float objspace_flatness_squared, int n)
+{
+   // @TODO this "flatness" calculation is just made-up nonsense that seems to work well enough
+   float dx0 = x1-x0;
+   float dy0 = y1-y0;
+   float dx1 = x2-x1;
+   float dy1 = y2-y1;
+   float dx2 = x3-x2;
+   float dy2 = y3-y2;
+   float dx = x3-x0;
+   float dy = y3-y0;
+   float longlen = (float) (sqrt(dx0*dx0+dy0*dy0)+sqrt(dx1*dx1+dy1*dy1)+sqrt(dx2*dx2+dy2*dy2));
+   float shortlen = (float) sqrt(dx*dx+dy*dy);
+   float flatness_squared = longlen*longlen-shortlen*shortlen;
+
+   if (n > 16) // 65536 segments on one curve better be enough!
+      return;
+
+   if (flatness_squared > objspace_flatness_squared) {
+      float x01 = (x0+x1)/2;
+      float y01 = (y0+y1)/2;
+      float x12 = (x1+x2)/2;
+      float y12 = (y1+y2)/2;
+      float x23 = (x2+x3)/2;
+      float y23 = (y2+y3)/2;
+
+      float xa = (x01+x12)/2;
+      float ya = (y01+y12)/2;
+      float xb = (x12+x23)/2;
+      float yb = (y12+y23)/2;
+
+      float mx = (xa+xb)/2;
+      float my = (ya+yb)/2;
+
+      tesselate_cubic(points, num_points, x0,y0, x01,y01, xa,ya, mx,my, objspace_flatness_squared,n+1);
+      tesselate_cubic(points, num_points, mx,my, xb,yb, x23,y23, x3,y3, objspace_flatness_squared,n+1);
+   } else {
+      add_point(points, *num_points,x3,y3);
+      *num_points = *num_points+1;
+   }
+}
+
+// returns number of contours
+static 
+Point *
+flatten(font·Vertex *vertices, int num_verts, float objspace_flatness, int **contour_lengths, int *num_contours, void *userdata)
+{
+   Point *points=0;
+   int num_points=0;
+
+   float objspace_flatness_squared = objspace_flatness * objspace_flatness;
+   int i,n=0,start=0, pass;
+
+   // count how many "moves" there are to get the contour count
+   for (i=0; i < num_verts; ++i)
+      if (vertices[i].type == font·Vmove)
+         ++n;
+
+   *num_contours = n;
+   if (n == 0) return 0;
+
+   *contour_lengths = malloc(sizeof(**contour_lengths) * n);
+
+   if (*contour_lengths == 0) {
+      *num_contours = 0;
+      return 0;
+   }
+
+   // make two passes through the points so we don't need to realloc
+   for (pass=0; pass < 2; ++pass) {
+      float x=0,y=0;
+      if (pass == 1) {
+         points = malloc(num_points * sizeof(points[0]));
+         if (!points)
+             goto error;
+      }
+      num_points = 0;
+      n= -1;
+      for (i=0; i < num_verts; ++i) {
+         switch (vertices[i].type) {
+            case font·Vmove:
+               // start the next contour
+               if (n >= 0)
+                  (*contour_lengths)[n] = num_points - start;
+               ++n;
+               start = num_points;
+
+               x = vertices[i].x, y = vertices[i].y;
+               add_point(points, num_points++, x,y);
+               break;
+            case font·Vline:
+               x = vertices[i].x, y = vertices[i].y;
+               add_point(points, num_points++, x, y);
+               break;
+            case font·Vcurve:
+               tesselate_curve(points, &num_points, x,y,
+                                        vertices[i].cx, vertices[i].cy,
+                                        vertices[i].x,  vertices[i].y,
+                                        objspace_flatness_squared, 0);
+               x = vertices[i].x, y = vertices[i].y;
+               break;
+            case font·Vcubic:
+               tesselate_cubic(points, &num_points, x,y,
+                                        vertices[i].cx, vertices[i].cy,
+                                        vertices[i].cx1, vertices[i].cy1,
+                                        vertices[i].x,  vertices[i].y,
+                                        objspace_flatness_squared, 0);
+               x = vertices[i].x, y = vertices[i].y;
+               break;
+         }
+      }
+      (*contour_lengths)[n] = num_points - start;
+   }
+
+   return points;
+error:
+   free(points);
+   free(*contour_lengths);
+   *contour_lengths = 0;
+   *num_contours = 0;
+   return nil;
+}
+
+void 
+font·rasterize(font·Bitmap *result, float flatness_in_pixels, font·Vertex *vertices, int num_verts, float scale_x, float scale_y, float shift_x, float shift_y, int x_off, int y_off, int invert, void *userdata)
+{
+   float scale            = scale_x > scale_y ? scale_y : scale_x;
+   int winding_count      = 0;
+   int *winding_lengths   = nil;
+   Point *windings = flatten(vertices, num_verts, flatness_in_pixels / scale, &winding_lengths, &winding_count, userdata);
+   if (windings) {
+      rasterize(result, windings, winding_lengths, winding_count, scale_x, scale_y, shift_x, shift_y, x_off, y_off, invert, userdata);
+      free(winding_lengths);
+      free(windings);
+   }
+}
+
+void 
+font·freebitmap(uchar *bm, void *userdata)
+{
+   free(bm);
+}
+
+uchar *
+font·glyph_makebitmap_subpixel(font·Info *info, float scale_x, float scale_y, float shift_x, float shift_y, int glyph, int *width, int *height, int *xoff, int *yoff)
+{
+   int ix0,iy0,ix1,iy1;
+   font·Bitmap gbm;
+   font·Vertex *vertices;
+   int num_verts = font·glyph_shape(info, glyph, &vertices);
+
+   if (scale_x == 0) scale_x = scale_y;
+   if (scale_y == 0) {
+      if (scale_x == 0) {
+         free(vertices);
+         return nil;
+      }
+      scale_y = scale_x;
+   }
+
+   font·glyph_bitmapbox_subpixel(info, glyph, scale_x, scale_y, shift_x, shift_y, &ix0,&iy0,&ix1,&iy1);
+
+   // now we get the size
+   gbm.w = (ix1 - ix0);
+   gbm.h = (iy1 - iy0);
+   gbm.pixels = nil; // in case we error
+
+   if (width ) *width  = gbm.w;
+   if (height) *height = gbm.h;
+   if (xoff  ) *xoff   = ix0;
+   if (yoff  ) *yoff   = iy0;
+
+   if (gbm.w && gbm.h) {
+      gbm.pixels = malloc(gbm.w * gbm.h);
+      if (gbm.pixels) {
+         gbm.stride = gbm.w;
+
+         font·rasterize(&gbm, 0.35f, vertices, num_verts, scale_x, scale_y, shift_x, shift_y, ix0, iy0, 1, info->userdata);
+      }
+   }
+   free(vertices);
+   return gbm.pixels;
+}
+
+uchar *
+font·glyph_makebitmap(font·Info *info, float scale_x, float scale_y, int glyph, int *width, int *height, int *xoff, int *yoff)
+{
+   return font·glyph_makebitmap_subpixel(info, scale_x, scale_y, 0.0f, 0.0f, glyph, width, height, xoff, yoff);
+}
+
+void 
+font·glyph_fillbitmap_subpixel(font·Info *info, uchar *output, int out_w, int out_h, int out_stride, float scale_x, float scale_y, float shift_x, float shift_y, int glyph)
+{
+   int ix0,iy0;
+   font·Vertex *vertices;
+   int num_verts = font·glyph_shape(info, glyph, &vertices);
+   font·Bitmap gbm;
+
+   font·glyph_bitmapbox_subpixel(info, glyph, scale_x, scale_y, shift_x, shift_y, &ix0,&iy0,0,0);
+   gbm.pixels = output;
+   gbm.w = out_w;
+   gbm.h = out_h;
+   gbm.stride = out_stride;
+
+   if (gbm.w && gbm.h)
+      font·rasterize(&gbm, 0.35f, vertices, num_verts, scale_x, scale_y, shift_x, shift_y, ix0,iy0, 1, info->userdata);
+
+   free(vertices);
+}
+
+void 
+font·glyph_fillbitmap(font·Info *info, unsigned char *output, int out_w, int out_h, int out_stride, float scale_x, float scale_y, int glyph)
+{
+   font·glyph_fillbitmap_subpixel(info, output, out_w, out_h, out_stride, scale_x, scale_y, 0.0f, 0.0f, glyph);
+}
+
+uchar *
+font·code_makebitmap_subpixel(font·Info *info, float scale_x, float scale_y, float shift_x, float shift_y, int codepoint, int *width, int *height, int *xoff, int *yoff)
+{
+   return font·glyph_makebitmap_subpixel(info, scale_x, scale_y,shift_x,shift_y, font·glyph_index(info,codepoint), width,height,xoff,yoff);
+}
+
+void 
+font·code_fillbitmap_subpixel_prefilter(font·Info *info, unsigned char *output, int out_w, int out_h, int out_stride, float scale_x, float scale_y, float shift_x, float shift_y, int oversample_x, int oversample_y, float *sub_x, float *sub_y, int codepoint)
+{
+   font·glyph_fillbitmap_subpixel_prefilter(info, output, out_w, out_h, out_stride, scale_x, scale_y, shift_x, shift_y, oversample_x, oversample_y, sub_x, sub_y, font·glyph_index(info,codepoint));
+}
+
+void 
+font·code_fillbitmap_subpixel(font·Info *info, unsigned char *output, int out_w, int out_h, int out_stride, float scale_x, float scale_y, float shift_x, float shift_y, int codepoint)
+{
+   font·glyph_fillbitmap_subpixel(info, output, out_w, out_h, out_stride, scale_x, scale_y, shift_x, shift_y, font·glyph_index(info, codepoint));
+}
+
+uchar *
+font·code_makebitmap(font·Info *info, float scale_x, float scale_y, int codepoint, int *width, int *height, int *xoff, int *yoff)
+{
+   return font·code_makebitmap_subpixel(info, scale_x, scale_y, 0.0f,0.0f, codepoint, width,height,xoff,yoff);
+}
+
+void 
+font·code_fillbitmap(font·Info *info, unsigned char *output, int out_w, int out_h, int out_stride, float scale_x, float scale_y, int codepoint)
+{
+   font·code_fillbitmap_subpixel(info, output, out_w, out_h, out_stride, scale_x, scale_y, 0.0f,0.0f, codepoint);
+}
+
+#define OVERMASK (SAMPLE-1)
+
+static 
+void 
+h_prefilter(uchar *pixels, int w, int h, int stride_in_bytes, unsigned int kernel_width)
+{
+   uchar buffer[SAMPLE];
+   int safe_w = w - kernel_width;
+   int j;
+   memset(buffer, 0, SAMPLE); // suppress bogus warning from VS2013 -analyze
+   for (j=0; j < h; ++j) {
+      int i;
+      unsigned int total;
+      memset(buffer, 0, kernel_width);
+
+      total = 0;
+
+      // make kernel_width a constant in common cases so compiler can optimize out the divide
+      switch (kernel_width) {
+         case 2:
+            for (i=0; i <= safe_w; ++i) {
+               total += pixels[i] - buffer[i & OVERMASK];
+               buffer[(i+kernel_width) & OVERMASK] = pixels[i];
+               pixels[i] = (uchar) (total / 2);
+            }
+            break;
+         case 3:
+            for (i=0; i <= safe_w; ++i) {
+               total += pixels[i] - buffer[i & OVERMASK];
+               buffer[(i+kernel_width) & OVERMASK] = pixels[i];
+               pixels[i] = (uchar) (total / 3);
+            }
+            break;
+         case 4:
+            for (i=0; i <= safe_w; ++i) {
+               total += pixels[i] - buffer[i & OVERMASK];
+               buffer[(i+kernel_width) & OVERMASK] = pixels[i];
+               pixels[i] = (uchar) (total / 4);
+            }
+            break;
+         case 5:
+            for (i=0; i <= safe_w; ++i) {
+               total += pixels[i] - buffer[i & OVERMASK];
+               buffer[(i+kernel_width) & OVERMASK] = pixels[i];
+               pixels[i] = (uchar) (total / 5);
+            }
+            break;
+         default:
+            for (i=0; i <= safe_w; ++i) {
+               total += pixels[i] - buffer[i & OVERMASK];
+               buffer[(i+kernel_width) & OVERMASK] = pixels[i];
+               pixels[i] = (uchar) (total / kernel_width);
+            }
+            break;
+      }
+
+      for (; i < w; ++i) {
+         assert(pixels[i] == 0);
+         total -= buffer[i & OVERMASK];
+         pixels[i] = (uchar) (total / kernel_width);
+      }
+
+      pixels += stride_in_bytes;
+   }
+}
+
+static 
+void 
+v_prefilter(uchar *pixels, int w, int h, int stride_in_bytes, unsigned int kernel_width)
+{
+   uchar buffer[SAMPLE];
+   int safe_h = h - kernel_width;
+   int j;
+   memset(buffer, 0, SAMPLE); 
+   for (j=0; j < w; ++j) {
+      int i;
+      unsigned int total;
+      memset(buffer, 0, kernel_width);
+
+      total = 0;
+
+      // make kernel_width a constant in common cases so compiler can optimize out the divide
+      switch (kernel_width) {
+         case 2:
+            for (i=0; i <= safe_h; ++i) {
+               total += pixels[i*stride_in_bytes] - buffer[i & OVERMASK];
+               buffer[(i+kernel_width) & OVERMASK] = pixels[i*stride_in_bytes];
+               pixels[i*stride_in_bytes] = (uchar) (total / 2);
+            }
+            break;
+         case 3:
+            for (i=0; i <= safe_h; ++i) {
+               total += pixels[i*stride_in_bytes] - buffer[i & OVERMASK];
+               buffer[(i+kernel_width) & OVERMASK] = pixels[i*stride_in_bytes];
+               pixels[i*stride_in_bytes] = (uchar) (total / 3);
+            }
+            break;
+         case 4:
+            for (i=0; i <= safe_h; ++i) {
+               total += pixels[i*stride_in_bytes] - buffer[i & OVERMASK];
+               buffer[(i+kernel_width) & OVERMASK] = pixels[i*stride_in_bytes];
+               pixels[i*stride_in_bytes] = (uchar) (total / 4);
+            }
+            break;
+         case 5:
+            for (i=0; i <= safe_h; ++i) {
+               total += pixels[i*stride_in_bytes] - buffer[i & OVERMASK];
+               buffer[(i+kernel_width) & OVERMASK] = pixels[i*stride_in_bytes];
+               pixels[i*stride_in_bytes] = (uchar) (total / 5);
+            }
+            break;
+         default:
+            for (i=0; i <= safe_h; ++i) {
+               total += pixels[i*stride_in_bytes] - buffer[i & OVERMASK];
+               buffer[(i+kernel_width) & OVERMASK] = pixels[i*stride_in_bytes];
+               pixels[i*stride_in_bytes] = (uchar) (total / kernel_width);
+            }
+            break;
+      }
+
+      for (; i < h; ++i) {
+         assert(pixels[i*stride_in_bytes] == 0);
+         total -= buffer[i & OVERMASK];
+         pixels[i*stride_in_bytes] = (uchar) (total / kernel_width);
+      }
+
+      pixels += 1;
+   }
+}
+
+static 
+float 
+oversample_shift(int oversample)
+{
+   if (!oversample)
+      return 0.0f;
+
+   // The prefilter is a box filter of width "oversample",
+   // which shifts phase by (oversample - 1)/2 pixels in
+   // oversampled space. We want to shift in the opposite
+   // direction to counter this.
+   return (float)-(oversample - 1) / (2.0f * (float)oversample);
+}
+
+// rects array must be big enough to accommodate all characters in the given ranges
+void 
+font·glyph_fillbitmap_subpixel_prefilter(font·Info *info, uchar *output, int out_w, int out_h, int out_stride, float scale_x, float scale_y, float shift_x, float shift_y, int prefilter_x, int prefilter_y, float *sub_x, float *sub_y, int glyph)
+{
+   font·glyph_fillbitmap_subpixel(info,
+                                 output,
+                                 out_w - (prefilter_x - 1),
+                                 out_h - (prefilter_y - 1),
+                                 out_stride,
+                                 scale_x,
+                                 scale_y,
+                                 shift_x,
+                                 shift_y,
+                                 glyph);
+
+   if (prefilter_x > 1)
+      h_prefilter(output, out_w, out_h, out_stride, prefilter_x);
+
+   if (prefilter_y > 1)
+      v_prefilter(output, out_w, out_h, out_stride, prefilter_y);
+
+   *sub_x = oversample_shift(prefilter_x);
+   *sub_y = oversample_shift(prefilter_y);
+}
+
+void 
+font·scaledvmetrics(uchar *fontdata, int index, float size, float *ascent, float *descent, float *lineGap)
+{
+   int i_ascent, i_descent, i_lineGap;
+   float scale;
+   font·Info info;
+   init(&info, fontdata, font·offsetfor(fontdata, index));
+   scale = size > 0 ? font·scaleheightto(&info, size) : font·scaleheighttoem(&info, -size);
+   font·vmetrics(&info, &i_ascent, &i_descent, &i_lineGap);
+   *ascent  = (float) i_ascent  * scale;
+   *descent = (float) i_descent * scale;
+   *lineGap = (float) i_lineGap * scale;
+}
+
+// -----------------------------------------------------------------------
+// sdf computation
+
+static 
+int 
+ray_intersect_bezier(float orig[2], float ray[2], float q0[2], float q1[2], float q2[2], float hits[2][2])
+{
+   float q0perp = q0[1]*ray[0] - q0[0]*ray[1];
+   float q1perp = q1[1]*ray[0] - q1[0]*ray[1];
+   float q2perp = q2[1]*ray[0] - q2[0]*ray[1];
+   float roperp = orig[1]*ray[0] - orig[0]*ray[1];
+
+   float a = q0perp - 2*q1perp + q2perp;
+   float b = q1perp - q0perp;
+   float c = q0perp - roperp;
+
+   float s0 = 0., s1 = 0.;
+   int num_s = 0;
+
+   if (a != 0.0) {
+      float discr = b*b - a*c;
+      if (discr > 0.0) {
+         float rcpna = -1 / a;
+         float d = (float) sqrt(discr);
+         s0 = (b+d) * rcpna;
+         s1 = (b-d) * rcpna;
+         if (s0 >= 0.0 && s0 <= 1.0)
+            num_s = 1;
+         if (d > 0.0 && s1 >= 0.0 && s1 <= 1.0) {
+            if (num_s == 0) s0 = s1;
+            ++num_s;
+         }
+      }
+   } else {
+      // 2*b*s + c = 0
+      // s = -c / (2*b)
+      s0 = c / (-2 * b);
+      if (s0 >= 0.0 && s0 <= 1.0)
+         num_s = 1;
+   }
+
+   if (num_s == 0)
+      return 0;
+   else {
+      float rcp_len2 = 1 / (ray[0]*ray[0] + ray[1]*ray[1]);
+      float rayn_x = ray[0] * rcp_len2, rayn_y = ray[1] * rcp_len2;
+
+      float q0d =   q0[0]*rayn_x +   q0[1]*rayn_y;
+      float q1d =   q1[0]*rayn_x +   q1[1]*rayn_y;
+      float q2d =   q2[0]*rayn_x +   q2[1]*rayn_y;
+      float rod = orig[0]*rayn_x + orig[1]*rayn_y;
+
+      float q10d = q1d - q0d;
+      float q20d = q2d - q0d;
+      float q0rd = q0d - rod;
+
+      hits[0][0] = q0rd + s0*(2.0f - 2.0f*s0)*q10d + s0*s0*q20d;
+      hits[0][1] = a*s0+b;
+
+      if (num_s > 1) {
+         hits[1][0] = q0rd + s1*(2.0f - 2.0f*s1)*q10d + s1*s1*q20d;
+         hits[1][1] = a*s1+b;
+         return 2;
+      } else {
+         return 1;
+      }
+   }
+}
+
+static 
+int 
+equal(float *a, float *b)
+{
+   return (a[0] == b[0] && a[1] == b[1]);
+}
+
+static 
+int 
+compute_crossings_x(float x, float y, int nverts, font·Vertex *verts)
+{
+   int i;
+   float orig[2], ray[2] = { 1, 0 };
+   float y_frac;
+   int winding = 0;
+
+   orig[0] = x;
+   orig[1] = y;
+
+   // make sure y never passes through a vertex of the shape
+   y_frac = (float) fmod(y, 1.0f);
+   if (y_frac < 0.01f)
+      y += 0.01f;
+   else if (y_frac > 0.99f)
+      y -= 0.01f;
+   orig[1] = y;
+
+   // test a ray from (-infinity,y) to (x,y)
+   for (i=0; i < nverts; ++i) {
+      if (verts[i].type == font·Vline) {
+         int x0 = (int) verts[i-1].x, y0 = (int) verts[i-1].y;
+         int x1 = (int) verts[i  ].x, y1 = (int) verts[i  ].y;
+         if (y > MIN(y0,y1) && y < MAX(y0,y1) && x > MIN(x0,x1)) {
+            float x_inter = (y - y0) / (y1 - y0) * (x1-x0) + x0;
+            if (x_inter < x)
+               winding += (y0 < y1) ? 1 : -1;
+         }
+      }
+      if (verts[i].type == font·Vcurve) {
+         int x0 = (int) verts[i-1].x , y0 = (int) verts[i-1].y ;
+         int x1 = (int) verts[i  ].cx, y1 = (int) verts[i  ].cy;
+         int x2 = (int) verts[i  ].x , y2 = (int) verts[i  ].y ;
+         int ax = MIN(x0,MIN(x1,x2)), ay = MIN(y0,MIN(y1,y2));
+         int by = MAX(y0,MAX(y1,y2));
+         if (y > ay && y < by && x > ax) {
+            float q0[2],q1[2],q2[2];
+            float hits[2][2];
+            q0[0] = (float)x0;
+            q0[1] = (float)y0;
+            q1[0] = (float)x1;
+            q1[1] = (float)y1;
+            q2[0] = (float)x2;
+            q2[1] = (float)y2;
+            if (equal(q0,q1) || equal(q1,q2)) {
+               x0 = (int)verts[i-1].x;
+               y0 = (int)verts[i-1].y;
+               x1 = (int)verts[i  ].x;
+               y1 = (int)verts[i  ].y;
+               if (y > MIN(y0,y1) && y < MAX(y0,y1) && x > MIN(x0,x1)) {
+                  float x_inter = (y - y0) / (y1 - y0) * (x1-x0) + x0;
+                  if (x_inter < x)
+                     winding += (y0 < y1) ? 1 : -1;
+               }
+            } else {
+               int num_hits = ray_intersect_bezier(orig, ray, q0, q1, q2, hits);
+               if (num_hits >= 1)
+                  if (hits[0][0] < 0)
+                     winding += (hits[0][1] < 0 ? -1 : 1);
+               if (num_hits >= 2)
+                  if (hits[1][0] < 0)
+                     winding += (hits[1][1] < 0 ? -1 : 1);
+            }
+         }
+      }
+   }
+   return winding;
+}
+
+static 
+float 
+cuberoot(float x)
+{
+   if (x<0)
+      return -(float) pow(-x,1.0f/3.0f);
+   else
+      return  (float) pow( x,1.0f/3.0f);
+}
+
+// x^3 + c*x^2 + b*x + a = 0
+static 
+int 
+solve_cubic(float a, float b, float c, float *r)
+{
+	float s = -a / 3;
+	float p = b - a*a / 3;
+	float q = a * (2*a*a - 9*b) / 27 + c;
+    float p3 = p*p*p;
+	float d = q*q + 4*p3 / 27;
+	if (d >= 0) {
+		float z = (float) sqrt(d);
+		float u = (-q + z) / 2;
+		float v = (-q - z) / 2;
+		u = cuberoot(u);
+		v = cuberoot(v);
+		r[0] = s + u + v;
+		return 1;
+	} else {
+	   float u = (float) sqrt(-p/3);
+	   float v = (float) acos(-sqrt(-27/p3) * q / 2) / 3; // p3 must be negative, since d is negative
+	   float m = (float) cos(v);
+       float n = (float) cos(v-3.141592/2)*1.732050808f;
+	   r[0] = s + u * 2 * m;
+	   r[1] = s - u * (m + n);
+	   r[2] = s - u * (m - n);
+
+   	return 3;
+   }
+}
+
+uchar * 
+font·glyph_sdf(font·Info *info, float scale, int glyph, int padding, uchar onedge_value, float pixel_dist_scale, int *width, int *height, int *xoff, int *yoff)
+{
+   float scale_x = scale, scale_y = scale;
+   int ix0,iy0,ix1,iy1;
+   int w,h;
+   uchar *data;
+
+   if (scale == 0) return nil;
+
+   font·glyph_bitmapbox_subpixel(info, glyph, scale, scale, 0.0f,0.0f, &ix0,&iy0,&ix1,&iy1);
+
+   // if empty, return nil
+   if (ix0 == ix1 || iy0 == iy1)
+      return nil;
+
+   ix0 -= padding;
+   iy0 -= padding;
+   ix1 += padding;
+   iy1 += padding;
+
+   w = (ix1 - ix0);
+   h = (iy1 - iy0);
+
+   if (width ) *width  = w;
+   if (height) *height = h;
+   if (xoff  ) *xoff   = ix0;
+   if (yoff  ) *yoff   = iy0;
+
+   // invert for y-downwards bitmaps
+   scale_y = -scale_y;
+
+   {
+      int x,y,i,j;
+      float *precompute;
+      font·Vertex *verts;
+      int num_verts = font·glyph_shape(info, glyph, &verts);
+      data = malloc(w * h);
+      precompute = malloc(num_verts * sizeof(float));
+
+      for (i=0,j=num_verts-1; i < num_verts; j=i++) {
+         if (verts[i].type == font·Vline) {
+            float x0 = verts[i].x*scale_x, y0 = verts[i].y*scale_y;
+            float x1 = verts[j].x*scale_x, y1 = verts[j].y*scale_y;
+            float dist = (float) sqrt((x1-x0)*(x1-x0) + (y1-y0)*(y1-y0));
+            precompute[i] = (dist == 0) ? 0.0f : 1.0f / dist;
+         } else if (verts[i].type == font·Vcurve) {
+            float x2 = verts[j].x *scale_x, y2 = verts[j].y *scale_y;
+            float x1 = verts[i].cx*scale_x, y1 = verts[i].cy*scale_y;
+            float x0 = verts[i].x *scale_x, y0 = verts[i].y *scale_y;
+            float bx = x0 - 2*x1 + x2, by = y0 - 2*y1 + y2;
+            float len2 = bx*bx + by*by;
+            if (len2 != 0.0f)
+               precompute[i] = 1.0f / (bx*bx + by*by);
+            else
+               precompute[i] = 0.0f;
+         } else
+            precompute[i] = 0.0f;
+      }
+
+      for (y=iy0; y < iy1; ++y) {
+         for (x=ix0; x < ix1; ++x) {
+            float val;
+            float min_dist = 999999.0f;
+            float sx = (float) x + 0.5f;
+            float sy = (float) y + 0.5f;
+            float x_gspace = (sx / scale_x);
+            float y_gspace = (sy / scale_y);
+
+            int winding = compute_crossings_x(x_gspace, y_gspace, num_verts, verts); // @OPTIMIZE: this could just be a rasterization, but needs to be line vs. non-tesselated curves so a new path
+
+            for (i=0; i < num_verts; ++i) {
+               float x0 = verts[i].x*scale_x, y0 = verts[i].y*scale_y;
+
+               // check against every point here rather than inside line/curve primitives -- @TODO: wrong if multiple 'moves' in a row produce a garbage point, and given culling, probably more efficient to do within line/curve
+               float dist2 = (x0-sx)*(x0-sx) + (y0-sy)*(y0-sy);
+               if (dist2 < min_dist*min_dist)
+                  min_dist = (float)sqrt(dist2);
+
+               if (verts[i].type == font·Vline) {
+                  float x1 = verts[i-1].x*scale_x, y1 = verts[i-1].y*scale_y;
+
+                  // coarse culling against bbox
+                  //if (sx > MIN(x0,x1)-min_dist && sx < MAX(x0,x1)+min_dist &&
+                  //    sy > MIN(y0,y1)-min_dist && sy < MAX(y0,y1)+min_dist)
+                  float dist = (float) fabs((x1-x0)*(y0-sy) - (y1-y0)*(x0-sx)) * precompute[i];
+                  assert(i != 0);
+                  if (dist < min_dist) {
+                     // check position along line
+                     // x' = x0 + t*(x1-x0), y' = y0 + t*(y1-y0)
+                     // minimize (x'-sx)*(x'-sx)+(y'-sy)*(y'-sy)
+                     float dx = x1-x0, dy = y1-y0;
+                     float px = x0-sx, py = y0-sy;
+                     // minimize (px+t*dx)^2 + (py+t*dy)^2 = px*px + 2*px*dx*t + t^2*dx*dx + py*py + 2*py*dy*t + t^2*dy*dy
+                     // derivative: 2*px*dx + 2*py*dy + (2*dx*dx+2*dy*dy)*t, set to 0 and solve
+                     float t = -(px*dx + py*dy) / (dx*dx + dy*dy);
+                     if (t >= 0.0f && t <= 1.0f)
+                        min_dist = dist;
+                  }
+               } else if (verts[i].type == font·Vcurve) {
+                  float x2 = verts[i-1].x *scale_x, y2 = verts[i-1].y *scale_y;
+                  float x1 = verts[i  ].cx*scale_x, y1 = verts[i  ].cy*scale_y;
+                  float box_x0 = MIN(MIN(x0,x1),x2);
+                  float box_y0 = MIN(MIN(y0,y1),y2);
+                  float box_x1 = MAX(MAX(x0,x1),x2);
+                  float box_y1 = MAX(MAX(y0,y1),y2);
+                  // coarse culling against bbox to avoid computing cubic unnecessarily
+                  if (sx > box_x0-min_dist && sx < box_x1+min_dist && sy > box_y0-min_dist && sy < box_y1+min_dist) {
+                     int num=0;
+                     float ax = x1-x0, ay = y1-y0;
+                     float bx = x0 - 2*x1 + x2, by = y0 - 2*y1 + y2;
+                     float mx = x0 - sx, my = y0 - sy;
+                     float res[3],px,py,t,it;
+                     float a_inv = precompute[i];
+                     if (a_inv == 0.0) { // if a_inv is 0, it's 2nd degree so use quadratic formula
+                        float a = 3*(ax*bx + ay*by);
+                        float b = 2*(ax*ax + ay*ay) + (mx*bx+my*by);
+                        float c = mx*ax+my*ay;
+                        if (a == 0.0) { // if a is 0, it's linear
+                           if (b != 0.0) {
+                              res[num++] = -c/b;
+                           }
+                        } else {
+                           float discriminant = b*b - 4*a*c;
+                           if (discriminant < 0)
+                              num = 0;
+                           else {
+                              float root = (float) sqrt(discriminant);
+                              res[0] = (-b - root)/(2*a);
+                              res[1] = (-b + root)/(2*a);
+                              num = 2; // don't bother distinguishing 1-solution case, as code below will still work
+                           }
+                        }
+                     } else {
+                        float b = 3*(ax*bx + ay*by) * a_inv; // could precompute this as it doesn't depend on sample point
+                        float c = (2*(ax*ax + ay*ay) + (mx*bx+my*by)) * a_inv;
+                        float d = (mx*ax+my*ay) * a_inv;
+                        num = solve_cubic(b, c, d, res);
+                     }
+                     if (num >= 1 && res[0] >= 0.0f && res[0] <= 1.0f) {
+                        t = res[0], it = 1.0f - t;
+                        px = it*it*x0 + 2*t*it*x1 + t*t*x2;
+                        py = it*it*y0 + 2*t*it*y1 + t*t*y2;
+                        dist2 = (px-sx)*(px-sx) + (py-sy)*(py-sy);
+                        if (dist2 < min_dist * min_dist)
+                           min_dist = (float) sqrt(dist2);
+                     }
+                     if (num >= 2 && res[1] >= 0.0f && res[1] <= 1.0f) {
+                        t = res[1], it = 1.0f - t;
+                        px = it*it*x0 + 2*t*it*x1 + t*t*x2;
+                        py = it*it*y0 + 2*t*it*y1 + t*t*y2;
+                        dist2 = (px-sx)*(px-sx) + (py-sy)*(py-sy);
+                        if (dist2 < min_dist * min_dist)
+                           min_dist = (float) sqrt(dist2);
+                     }
+                     if (num >= 3 && res[2] >= 0.0f && res[2] <= 1.0f) {
+                        t = res[2], it = 1.0f - t;
+                        px = it*it*x0 + 2*t*it*x1 + t*t*x2;
+                        py = it*it*y0 + 2*t*it*y1 + t*t*y2;
+                        dist2 = (px-sx)*(px-sx) + (py-sy)*(py-sy);
+                        if (dist2 < min_dist * min_dist)
+                           min_dist = (float) sqrt(dist2);
+                     }
+                  }
+               }
+            }
+            if (winding == 0)
+               min_dist = -min_dist;  // if outside the shape, value is negative
+            val = onedge_value + pixel_dist_scale * min_dist;
+            if (val < 0)
+               val = 0;
+            else if (val > 255)
+               val = 255;
+            data[(y-iy0)*w+(x-ix0)] = (uchar) val;
+         }
+      }
+      free(precompute);
+      free(verts);
+   }
+   return data;
+}
+
+uchar * 
+font·code_sdf(font·Info *info, float scale, int codepoint, int padding, uchar onedge_value, float pixel_dist_scale, int *width, int *height, int *xoff, int *yoff)
+{
+   return font·glyph_sdf(info, scale, font·glyph_index(info, codepoint), padding, onedge_value, pixel_dist_scale, width, height, xoff, yoff);
+}
+
+void 
+font·freesdf(uchar *bitmap, void *userdata)
+{
+   free(bitmap);
+}
+
+char*
+font·name(font·Info *font, int *length, int platformID, int encodingID, int languageID, int nameID)
+{
+   int32 i,count,stringOffset;
+   uchar *fc = font->data;
+   uint32 offset = font->fontstart;
+   uint32 nm = find_table(fc, offset, "name");
+   if (!nm) return nil;
+
+   count = ttUSHORT(fc+nm+2);
+   stringOffset = nm + ttUSHORT(fc+nm+4);
+   for (i=0; i < count; ++i) {
+      uint32 loc = nm + 6 + 12 * i;
+      if (platformID == ttUSHORT(fc+loc+0) && encodingID == ttUSHORT(fc+loc+2)
+          && languageID == ttUSHORT(fc+loc+4) && nameID == ttUSHORT(fc+loc+6)) {
+         *length = ttUSHORT(fc+loc+8);
+         return (char *) (fc+stringOffset+ttUSHORT(fc+loc+10));
+      }
+   }
+   return nil;
+}
+
+#if 0
+static 
+int 
+matchpair(uchar *fc, uint32 nm, uchar *name, int32 nlen, int32 target_id, int32 next_id)
+{
+   int32 i;
+   int32 count = ttUSHORT(fc+nm+2);
+   int32 stringOffset = nm + ttUSHORT(fc+nm+4);
+
+   for (i=0; i < count; ++i) {
+      uint32 loc = nm + 6 + 12 * i;
+      int32 id = ttUSHORT(fc+loc+6);
+      if (id == target_id) {
+         // find the encoding
+         int32 platform = ttUSHORT(fc+loc+0), encoding = ttUSHORT(fc+loc+2), language = ttUSHORT(fc+loc+4);
+
+         // is this a Unicode encoding?
+         if (platform == 0 || (platform == 3 && encoding == 1) || (platform == 3 && encoding == 10)) {
+            int32 slen = ttUSHORT(fc+loc+8);
+            int32 off = ttUSHORT(fc+loc+10);
+
+            // check if there's a prefix match
+            int32 matchlen = CompareUTF8toUTF16_bigendian_prefix(name, nlen, fc+stringOffset+off,slen);
+            if (matchlen >= 0) {
+               // check for target_id+1 immediately following, with same encoding & language
+               if (i+1 < count && ttUSHORT(fc+loc+12+6) == next_id && ttUSHORT(fc+loc+12) == platform && ttUSHORT(fc+loc+12+2) == encoding && ttUSHORT(fc+loc+12+4) == language) {
+                  slen = ttUSHORT(fc+loc+12+8);
+                  off = ttUSHORT(fc+loc+12+10);
+                  if (slen == 0) {
+                     if (matchlen == nlen)
+                        return 1;
+                  } else if (matchlen < nlen && name[matchlen] == ' ') {
+                     ++matchlen;
+                     if (font·CompareUTF8toUTF16_bigendian((char*) (name+matchlen), nlen-matchlen, (char*)(fc+stringOffset+off),slen))
+                        return 1;
+                  }
+               } else {
+                  // if nothing immediately following
+                  if (matchlen == nlen)
+                     return 1;
+               }
+            }
+         }
+
+         // @TODO handle other encodings
+      }
+   }
+   return 0;
+}
+
+static 
+int 
+matches(uchar *fc, uint32 offset, uchar *name, int32 flags)
+{
+   int32 nlen = (int32) strlen((char *) name);
+   uint32 nm, hd;
+   if (!isfont(fc+offset)) 
+       return 0;
+
+   // check italics/bold/underline flags in macStyle...
+   if (flags) {
+      hd = find_table(fc, offset, "head");
+      if ((ttUSHORT(fc+hd+44) & 7) != (flags & 7)) return 0;
+   }
+
+   nm = find_table(fc, offset, "name");
+   if (!nm) return 0;
+
+   if (flags) {
+      // if we checked the macStyle flags, then just check the family and ignore the subfamily
+      if (matchpair(fc, nm, name, nlen, 16, -1))  return 1;
+      if (matchpair(fc, nm, name, nlen,  1, -1))  return 1;
+      if (matchpair(fc, nm, name, nlen,  3, -1))  return 1;
+   } else {
+      if (matchpair(fc, nm, name, nlen, 16, 17))  return 1;
+      if (matchpair(fc, nm, name, nlen,  1,  2))  return 1;
+      if (matchpair(fc, nm, name, nlen,  3, -1))  return 1;
+   }
+
+   return 0;
+}
+
+int 
+font·findmatch(uchar *font_collection, char *name_utf8, int32 flags)
+{
+   int32 i;
+   for (i=0;;++i) {
+      int32 off = font·offsetfor(font_collection, i);
+      if (off < 0) return off;
+      if (matches((uchar *) font_collection, off, (uchar*) name_utf8, flags))
+         return off;
+   }
+}
+#endif
diff --git a/sys/libfont/rules.mk b/sys/libfont/rules.mk
new file mode 100644
index 0000000..af3e8fa
--- /dev/null
+++ b/sys/libfont/rules.mk
@@ -0,0 +1,19 @@
+include share/push.mk
+# Iterate through subdirectory tree
+
+# Local sources
+SRCS_$(d) := $(d)/font.c
+LIBS_$(d) := $(d)/libfont.a
+TSTS_$(d) := $(d)/test.c
+
+include share/paths.mk
+
+# Local rules
+$(LIBS_$(d)): $(OBJS_$(d))
+	$(ARCHIVE)
+
+$(UNTS_$(d)): TCLIBS := $(LIBS_$(d)) $(OBJ_DIR)/libn/libn.a
+$(UNTS_$(d)): $(TOBJS_$(d)) $(LIBS_$(d))
+	$(LINK)
+
+include share/pop.mk
diff --git a/sys/libfont/test.c b/sys/libfont/test.c
new file mode 100644
index 0000000..b92a56f
--- /dev/null
+++ b/sys/libfont/test.c
@@ -0,0 +1,62 @@
+#include <u.h>
+#include <libn.h>
+#include <libfont.h>
+
+#define STB_IMAGE_WRITE_IMPLEMENTATION
+#include "stb_image_write.h"
+
+#define W 512
+#define H 128
+#define L 64
+
+static char *phrase = "the quick brown";
+
+int
+main()
+{
+    int i, err;
+    float  scale;
+    uchar *bitmap;
+    font·Info *info;
+    mmap·Reader fontfile;
+    int x, y, as, ds, lg, ax, lsb, off, kern, r[2], c0[2], c1[2];
+
+    err = 0;
+    fontfile = mmap·open("/home/nolln/root/data/DejaVuSans.ttf");
+    if (!fontfile.len) {
+        err = 1;
+        goto end;
+    }
+    info   = font·make(fontfile.ubuf, 0);
+    if (!info) 
+        panicf("failed to load info");
+
+    bitmap = calloc(W*H, sizeof(*bitmap)); 
+    scale  = font·scaleheightto(info, L);
+
+    font·vmetrics(info, &as, &ds, &lg);
+    as *= scale;
+    ds *= scale;
+
+    x = 0;
+    for (i = 0; i < strlen(phrase); i++) {
+        font·code_hmetrics(info, phrase[i], &ax, &lsb);
+        font·code_bitmapbox(info, phrase[i], scale, scale, c0, c0+1, c1, c1+1);
+
+        y   = as + c0[1];
+        off = x + lsb * scale + y * W; 
+        font·code_fillbitmap(info, bitmap+off, c1[0]-c0[0], c1[1]-c0[1], W, scale, scale, phrase[i]);
+
+        x += ax * scale;
+        kern = font·code_kernadvance(info, phrase[i], phrase[i+1]);
+        x += kern * scale;
+    }
+
+    stbi_write_png("out.png", W, H, 1, bitmap, W);
+
+    font·free(info);
+    free(bitmap);
+end:
+    mmap·close(fontfile);
+    return err;
+}